UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA THE SNOWY TREE CRICKET AND OTHER INSECTS INJURIOUS TO RASPBERRIES LESLIE M. SMITH BULLETIN 505 DECEMBER, 1930 UNIVERSITY OF CALIFORNIA PRINTING OFFICE BERKELEY, CALIFORNIA THE SNOWY TREE CRICKET AND OTHER INSECTS INJURIOUS TO RASPBERRIES LESLIE M. SMITHi For several years prior to 1928 the raspberry growers in the Santa Clara Valley suffered considerable loss from the attacks of various insects, the most destructive being the snowy tree cricket, Oecanthus niveus (De Geer). The study reported in this paper was begun in May of 1927 and continued through the summer of 1929. During this period the snowy tree cricket received particular attention, while the other insect pests of raspberries were studied as much as available time permitted. These insects are listed below : The black vine weevil, Brachyrhinus sulcatus Fabr. The rough strawberry weevil, Brachyrhinus rugosostriatus Goeze. The strawberry root worm, Paria canella var. quadrinotata (Say). The strawberry crown moth, Synanthedon bibionipennis Bdv. The raspberry crown borer, Bembecia marginata (Harris). The common red spider, Tetranychus telarius (Linn.). The blue sharpshooter, Cicadella circellata (Baker). Fuller's rose weevil, Pantomorus godmani (Crotch). The raspberry horntail, Hartigia cressoni (Kirby). The California tree cricket, Oecanthus calif ornicus Saussure. LIFE HISTORY OF THE SNOWY TREE CRICKET The snowy tree cricket, Oecanthus niveus (De Geer), is divided by Fulton 2 into two physiological varieties: Race A living in trees and singing 160 notes a minute at 70° F and race B living in bushes and singing 90 notes a minute. Although both forms were encoun- tered in the raspberry patches, specimens of race A were rarely found while race B occurred in enormous numbers. These two forms were detected by the difference in the rate of stridulating. The males syn- chronize when singing, so that thousands singing together resemble the song of a single specimen. Occasional males of race A were not able to synchronize with race B and could be detected easily by ear. 1 Assistant in Entomology and Parasitology. 2 Fulton, B. B. The tree crickets of Oregon. Oregon Agr. Exp. Sta. Bui. 223:1-20, fig. 1-8. 1926. University of California — Experiment Station Fi , r . i._Adult male snowy tree cricket and egg punctures in a raspberry cane. Bul. 505] The Snowy Tree Cricket and Other Insects 5 The snowy tree cricket deposits its eggs in punctures in long rows in the canes of the raspberries. Each puncture (fig. 1) is distinct and more or less circular in outline so that the row of eggs is repre- sented outwardly by a series of dots. The eggs are laid through the outer layer of w T ood and placed diagonally across the pith. They are '.,'r'^'^-' : '■ ^ ''.'';■ ;y y ''y : ^P/::^: rf-'";«;4.";^ k/v ;'v:' • ■ ,...;,; ; : {; - • \ "JM;i*k : yi>s'0:At >ix- '&'y : S : '~.:'r~:.- I*: :~v ;• : W :: l ^^^ '.. "v;p%r~ ~\ "■"■ "*« ' ' ■ ' ; --^- J 'W: : -:^%, ■■■,-. ; 1 DBHJT ^j&jg**- ^HB \ i'MS' : ->-5i*>C*K::d*: ■ Vj v ■ Bt ' ,. : .: ' ; -: ■'. .: ''■'■'■fly-. ■ ' "l, ? •*■' ^| H ^v%toj^^H^9 .■-^■■'Vl.!':,-;,-:-'-:;:^ !. ■" f . - - ' * -4iK* . : V H 'tfEr 1 'jfct^.. ■■.■■■■■ \- ■ : '*xy : ; ^^^9 • ^iHffl ■'^■■:y.'X ■ - " 1 ■" ■ ■ ' ' ■' -^ ^'.^^ "" .'-'I '■'"'*',:..- : -.' ■' ■■■■■■■ " " ■■• 't ■"' ' '}' '.■ ^'j| \ " . ■:::.*-.■ it..' * 1 - * '" ^ .'■** .... ' !^H . ■'.'■v3:> > ''tv... '■ ^k. '*?3fli^l Br • y JF '^w/ ***3c? ■ : i\'W. ■:■■?■*£ flflBi '^''i^V^i* ^ : ; > :; ;l^^fe;-.'. £"* - ; ;-*■ i ^ 3 - *"■ > , * *~ * ■■■■■■■■' : , flPJ/ Bm. • ''■ : ...y' : '..\-'- : -- : *=;:"■ ''^BBJnrH' ' Hp- V% ' ■■'-'" * " .'■":".::v > "'v : - •"■ Bjw ' -4 j" ^ Fig. 2. — Nymphs of the snowy tree cricket on raspberry leaf. yellow in color, cylindrical, elongate, and slightly curved. On the end of the egg towards the ovipositional puncture is a white, shell- like cap bearing minute projections. Beyond the cap, the ovipositional cavity contains a small quantity of dried foam which is no doubt secreted by the female. External to this, the cavity is capped by a plug of chewed wood. Although outwardly the egg punctures 6 University of California — Experiment Station may form a single straight line, the eggs themselves are generally alternately slanted into two rows, like the teeth of a saw. This arrangement precludes the possibility of puncturing a previously laid egg while drilling the cavity for the next. The first eggs were found in the field on August 16, 1927. Eggs kept indoors during most of the winter began hatching March 15. Eggs in the field hatched much later. The first newly hatched nymph was captured in the field on April 18. On May 23, 1928, a count of 316 eggs collected in the field showed 97.2 per cent hatched. The season was somewhat later in 1929 when on May 17 an examination of eggs in the field showed 43.1 per cent hatched and on June 7, 87.3 per cent hatched. The newly hatched nymph is whitish, slender, and very fragile in appearance. When accidentally jarred from the leaves they spread their legs and antennae to the sides and front and this so increases their air resistance that they float slowly down. There are five molts, the last one of which gives rise to the adult condition. Thus there are five nymphal stages. In the later stages the crickets become green, to pale greenish-yellow, with white, opaque blotches arranged in rows on the abdomen (fig. 2). During the nymphal period in 1928, collec- tions of the field run of crickets were made by beating into a net and preserving all specimens. These were then separated according to instars and counted as in table 1. TABLE 1 Nymphal Development of Oecanthus niveus in the Fieli> in 1928 First mstar Second instar Third instar Fourth instar Fifth instar Adults Date Num- Per Num- Per Num- Per Num- Per Num- Per Num- Per ber cent ber cent ber cent ber cent ber cent ber cent June 4 31 32 3 45 46.9 20 20 8 June 12 22 31 4 38 54 3 9 12.9 1 1.4 June 25 6 13 20 43 4 18 39 2 2 4.4 July 18 1 18 2 3.6 13 23 7 29 52.8 10 18.1 The nymphs -are omnivorous and feed on a variety of plant and animal tissue. In the laboratory the entire nymphal period was com- pleted on an exclusive diet of aphids. They are cannibalistic and in captivity frequently kill and eat weaker and smaller members of their species. The length of the nymphal period was determined indoors by rearing fifteen nymphs from the egg to the adult condition, with aphids for food. These nymphs were kept isolated in petri dishes. Bul. 505] The Snowy Tree Cricket and Other Insects 7 The minimum time required from hatching to the adult stage was 44 days; the maximum was 66; and the average was 55.7 days. It was interesting to note that the males averaged 9 days longer for their development than the females. The largest nymphs collected in the field were kept in cages out-of-doors to determine the earliest appear- ance of adults. Two adults appeared in these cages on June 28. The adult crickets (fig. 1) are about % inch long, green or greenish-white in color. Both sexes are fully winged; the wings of the male are broadened toward the posterior end, while those of the female taper regularly to a point. The crickets are capable of cover- ing 50 or 75 feet at a single flight. They rarely take wing, however, and then only as a result of being disturbed. It would seem that flight is not used as a means of dispersal. They spend the day, as do the nymphs also, hiding under leaves of the raspberry bushes. They are completely concealed from above, except for the antennae which generally protrude from under the edge of the leaf. At night they become active and by the aid of a flashlight can be seen actively run- ning over the foliage, or feeding. In the morning they are practically all to be found on the sunny side of the rows, but in the afternoon, especially on warm days, they seek the shady side. They spend their entire lives in the upper half of the bushes, never going lower by choice ; and if knocked down, they quickly climb back into the tops. In large berry patches, where the crickets are not numerous enough to crowd one another into a uniform distribution, they manifest gregarious tendencies. It was at first believed that this apparent gregariousness was the result of driving winds which would tend to concentrate the crickets in the down-wind corner of the patch. It was found that while this may be the case to some extent, it failed to account for all of the spotty distribution. It seemed likely that populous groups originated from eggs in stacks of prunings here and there in the field but this likewise failed to account for the majority of colonies. Consequently, it seems that the crickets exhibit true gregarious tendencies, possibly drawn together by the singing of the males. In order to determine the length of the preovipositional period, ten newly emerged adult females were each isolated with one male in lamp chimneys surrounding a raspberry cane. In addition to the leaves of the raspberry included in the cage, the crickets were fed on fresh fruit. A high mortality occurred in the crickets so caged; so that only three pairs lived to oviposit. Two of these females showed a preovipositional period of 32 days and one of 31 days. 8 University of California — Experiment Station In an attempt to determine the maximum number of egg's which one female can lay, 7 adult females, newly emerged, were isolated in various types of cages out-of-doors, with one or two males. These crickets were allowed to live in the cages until they died a natural death. During this time they were fed on fresh fruit. Sufficient water condensed on the inside of the cages to quench their thirst. After the death of the females the eggs were counted. The three highest numbered 41, 50 and 51 eggs respectively. It was not possible to determine the number of eggs laid by any one female in the field. In view of the usual cultural practices of pruning and the removal of old canes, it seemed essential to obtain data on the preference of types of canes for oviposition. In September, in the midst of the egg laying period, there are three types of canes often present in the patch: (1) canes grown during the current spring which bore the second crop, green at this time of 3 r ear; (2) canes grown in the spring of the preceding year which bore the first crop of the current year, dead at this time; (3) canes grown in the spring two years before which bore the second crop of the preceding year. Canes of this third class are dead and dry, with the papery epidermis beginning to scale off. Ten females, all previously mated, were placed in a cage with equal amounts of the three types of canes. At the end of seventeen days the eggs were counted. Canes of the first type contained 319 eggs ; of the second type, 2 eggs ; and of the third type, no eggs. ' It was noticed that in the field decided preference is shown for the upper one-third of the canes for oviposition, and particularly those parts of the cane which are bent out of a perpendicular position. Fully grown canes were cut into three equal sections representing base, middle, and top. These were then placed in a bell jar with egg laying females. All three sections were on the same level and all inclined at about 70 degrees. Eggs were laid as follows: bases, 87; middle, 8 ; tops, 28. This indicates that the height of the cane is the determining factor in its selection for egg deposition, and that when all sizes of wood are on the same level, the larger wood is somewhat preferred. The adults appear in the field about the middle of July and live until the heavy frosts of winter. One female was seen ovipositing in the field on November 21 and males were occasionally heard singing later than this date. Damage Done by the Snowy Tree Cricket. — The first three instars of 0. niveus do practically no damage to the raspberries. The majority of the crickets pass through the third instar during the decline in Bul. 505] The Snowy Tree Cricket and Other Insects 9 production of the first crop. Damage becomes apparent in the inter- crop period which occurs usually in the early or the middle part of July. The damage increases until the end of the blooming period. The fourth and fifth instars, and especially the adults, are greatly attracted by the flowers, and seem to feed on them almost exclusively. The stamens, pistils and petals are preferred to the sepals. Flower buds, beginning to open, with the petals just showing white beyond the sepals, are also attacked. In these, the petals and sepals are eaten ; occasionally a hole is made through these parts and some of the stamens and pistils eaten. The raspberry flower loses its petals within Fig. 3. — Damage done by the snowy tree cricket to flowers and fruit of the Eanaree raspberry. In the upper left is shown a normal flower. one day after blooming so that in many cases only stamens and pistils remain as food for the crickets. In the case of severely injured flowers, it may be seen that all of the pistils and stamens have been eaten, and in some cases the receptacle as well (fig. 3). Owing to the nervous habits and rapid movements of these insects it rarely happens that a flower is completely consumed. Usually a small group of stamens or a few pistils are eaten, then the cricket moves to a fresh flower. As a result the injured flower gives rise to a berry having fewer than the normal number of drupelets. Often such flowers mature only three or four drupelets and are entirely worthless. Others may mature more drupelets and to the inexperienced eye appear to be normal berries, but when picked they crumble ; that is, the drupelets separate, since apparently the loss of a few drupelets 10 University of California — Experiment Station results in loss of lateral pressure, necessary to unite the drupelets into a firm berry. The crickets increased in numbers in the berry patches in the Santa Clara Valley until in 1925, 1926, and 1927 in certain patches they took every flower of the second crop. The few berries which reached maturity were generally weakly knit and crumbled when picked. To some extent the raspberry can overcome the damage to the flowers in that each cane can produce more flowers than it can mature fruit. The terminal and distal buds flower first and if allowed to mature, the buds lower on the cane may never flower. If, however, the distal flowers are removed the lower buds bloom and replace those which were injured. But in recent years the crickets have been sufficiently numer- ous to consume all flowers, including the secondarily developed ones. The relation between the number of crickets present in the berry patch and the amount of damage they produce was rather difficult to measure. In an attempt to obtain data on this point the bushes were separated in the middle of the row and half the canes (on the side of the row nearest the observer) were bent over and shaken so that the crickets on them would fall on the ground in between the rows. These were counted before they succeeded in jumping back into the bushes. In this manner by advancing slowly along a row, bending half the canes and shaking them, a fairly comparative count of the number of crickets on one side of the row was obtained. After determining the number of crickets in a given piece of row the flowers and fruit were counted and the number of damaged ones recorded. The amount of damage increases steadily in the summer and fall until it reaches 100 per cent in the heaviest infestations. The counts given in table 2 do not show this fact because the counts are taken from different patches, and under different conditions. Thus on August 4 a very heavy infestation showed damage amounting to between 30 and 40 per cent, but this was exceptional. TABLE 2 Relation Between Amount of Damage and Number, of Crickets Present Date Number of crickets Length of row Cone side) in feet Number of crickets to 100 feet of row Damage, per cent July 28 15 17 5 7 17 21 300 48 36 24 24 24 5 35 14 29 71 87 .1 Sept. 11 3 Sept. 28 10 Sept. 28 20 Sept. 28 25 Sept. 28 50 Btjl. 505] The Snowy Tree Cricket and Other Insects 11 The adults occasionally feed on the leaves of the raspberry. In cages this damage was rather serious, but in the field it seems to be negligible. A certain amount of damage results from the ovipositional punctures. In badly infested patches favorably situated canes fre- quently contain 300 to 400 eggs and this number of punctures is weak- ening to the cane. The eggs are laid almost exclusively in canes which bear the fall crop. These canes bear the spring crop of the following year and when heavily loaded with fruit they occasionally break at the point of insertion of eggs. However, actual breakage of canes is not very common. It seemed likely that the numerous ovipositional punctures might affect fruit bearing, causing a reduction in the size of the berries. In an experimentally-dusted patch there were no eggs, while in the check area adjoining, there were from 50 to 250 eggs to a cane. Thirty-five ounces of fruit from the dusted area contained 859 berries, or 24,5 berries per ounce ; while from the check area 33 ounces contained 793 berries, or 24.2 berries per ounce, showing practically no difference in the size of the berries from canes with and without egg punctures. Varieties of Raspberries Attacked. — In the Santa Clara Valley the Ranaree (St. Regis) is almost the only variety grown. Consequently this study pertains to that variety. A patch of La France berries con- tiguous to Ranaree was observed from time to time. Beating 100 feet of row of La France gave three crickets while 100 feet of row in the patch of Ranarees adjoining, gave fifteen. No damage was noted on the La France at any time. EXPERIMENTS ON THE CONTROL OF THE SNOWY TREE CRICKET Natural agencies play a considerable role in the control of this pest. The most effective natural check appears to be produced by four species of hymenopterous egg parasites. These parasites are Macro- rileya oecanthi Ashm., Cacellus oecanthi Ashm., Eupelmus sp., and Aprostocetus sp. The largest and most important of these is Macro- rileya oecanthi. The adults of this parasite have greatly elongated cylindrical bodies, 5 to 6 millimeters long, and black in color. The abdomen of the female projects considerably beyond the wings which, therefore, appear very short and inadequate for flight. Both sexes fly well, however. The female of M. oecanthi (fig. 4) is provided with a long ovipositor with which she pierces the plug of chewed wood pro- tecting the egg of Oecanthus niveus, and places a small, white oval egg near the base of the host egg. Frequently the outer shell of the cricket 12 University of California — Experiment Station egg is broken as though to facilitate its puncturing by the young parasite larva after hatching. The newly hatched larva of M . oecanthi first consumes the egg upon which it finds itself, then burrows through the pith channel of the cane until it encounters another egg which is likewise eaten. The number of eggs eaten in this manner or injured so that molds get into them varies from 10 to 15 for each larva. Pupa- tion occurs within the larval tunnels in the pith and the adults emerge by cutting a small circular hole through the bark. Fig. 4.— Adult female of the egg parasite, Macrorileya oecanthi Ashm. Eggs were laid in the laboratory in the early part of October. They may be laid in the field considerably later. The duration of the egg stage is unknown but it is probably very short since eggs laid September 7 had produced what appeared to be mature larvae by November 2 when these were dissected out. Larvae pupated in petri dishes and from these the pupal period was found to be from 13 to 18 days. Adults began to emerge from canes brought into the labora- tory on August 2. The main period of emergence occurred through the month of September. The percentage of parasitism by M. oecanthi varied greatly for different sections. A bundle of canes gathered at random in the field and kept in the laboratory yielded 134 crickets and 4 specimens of M. oecanthi. If each parasite destroyed 10 eggs as would probably be the case, the destruction of eggs would be 22.9 per cent. Bul. 505] The Snowy Tree Cricket and Other Insects 13 Cacellus oecanthi Ashm. is a small, dark, reddish-brown insect with lighter brown legs. The head is nearly spherical and the abdomen is almost regularly elliptical, not broadened at either base or apex. The antennae of the male are filiform while those of the female are capitate. Mating and oviposition occurred in the laboratory. Although larvae and pupae were not identified it is almost certain, from numerous dis- sections, that each specimen of this species destroys one cricket egg only. Oviposition occurred in the laboratory on August 20 and 27. Adults emerged in the laboratory from July 19 until October 2. Enpelmus sp. is a small insect measuring about 2% mm - i n length. The body is slender, elongated and straight sided. These insects appear black to the unaided eye, but when magnified are seen to be dark metallic green. The adults run rapidly and fly readily. Adults emerged in the laboratory from field material from May 30 until Sep- tember 29. Oviposition was witnessed on August 30 in the laboratory. Several attempts were made to rear this parasite through its life cycle. In one case three larvae were obtained from eggs laid under cage conditions. These eggs were laid on September 6 and the larvae were dissected out of the raspberry cane on December 13 and at this time were apparently mature. The larvae are whitish in color, with a distinct head, and only the mandibles are darkly chitinized. They were found one in each egg cavity and had eaten one cricket egg apiece. The body is not pointed in the rear. The last segment is capable of being dented in as a sucking disk. The larvae are fairly active. Aprostocetus sp. is black, about 2 mm. in length. The abdomen of the male is spindle shaped while that of the female is top shaped. Adults emerged in the laboratory from June 30 until August 2 ; adults were captured in the field on August 30, September 13, and October 14. Mating occurred in the laboratory. Adults were reared from larvae lying free in petri dishes. Each larva consumes one egg and when fully grown it backs out of the egg cavity, forces its way into the pith, and pupates just below the position of the egg cavity. The pupal period in the laboratory in petri dishes varied from 13 to 18 days. This species was also reared from eggs of Oecanthus nigricornis quadripunctatus Beutenmuller. A record was kept of the emergence* of all parasites from all material brought into the laboratory from various sources. The total emergence of each species was as follows : Macrorileya oecanthi, 102 ; Aprostocetus sp., 141 ; Eupelmus sp., 30 ; and Cacellus oecanthi, 22. If each specimen of M . oecanthi devoured 10 eggs, then this species is by far the most important of the egg parasites. 14 University of California — Experiment Station The only predators which seem to exercise any control on the crickets are large, orb-weaving spiders. These were unusually abun- dant in one locality and seemed to be a considerable factor in cricket control. The normal cultural practice of pruning the raspberry canes is a very large factor in control. The eggs are laid in canes which bore the second crop on their terminal growth. These terminals are nor- mally pruned off at a height determined by the size and vigor of the cane. The pruned canes put forth lateral growth in the early spring, which bears the first crop of that year. As was stated before, the crickets inhabit the upper one-third of the bushes and it is in this part that the majority of eggs are laid. At pruning, great numbers of eggs are removed in the prunings and, depending upon the severity of the pruning, from 50 to 75 per cent of the eggs may be removed. If prun- ings are allowed to lie on the ground all winter the young crickets hatch successfully and have no difficulty in jumping onto the bushes. Hence, it is very important that all prunings be burned before March 15, that is, before any of the eggs are allowed to hatch. Artificial control measures involving the use of sprays are difficult to apply owing to the type of culture under which the berries are grown. The hedgerow system is used almost exclusively since it is admirably adapted to the Ranaree variety. The rows are generally one or two feet wide, with a row every six feet. In patches with a dense growth the canes of adjacent rows are frequently in contact by late summer. It is thus impossible to draw a spray rig between the rows. Some patches are laid out with frequent roads crossing the rows of berries. These patches could be sprayed by keeping the rig on the road and walking into the patch with a sufficient length of hose. This usually would require extra long hose and would necessitate much walking and moving of hose. Thus spraying is attended by consider- able difficulty. However, several sprays were tried out, using a knapsack sprayer. The following proprietary mixtures were tested : Volck at 2 per cent (2 parts Volck to 100 parts water) ; Petrotine at 2 per cent; Derrisol at .25 per cent (1 part to 400) ; Destruxol at .25 per cent; Black Leaf 40 at .2 per cent; and Evergreen .25 per cent with whale oil soap .25 per cent. Each of these was applied to 15 feet of row in the field. The Volck was applied at the rate of 1 gallon to 15 feet (i.e., 480 gal- lons per acre) ; and the Petrotine was used at the rate of % gallon to 15 feet, the two sprays being applied on May 28 at which time the majority of crickets were in the first and second instars. The portion to be used in the test was underlaid on both sides by strips of black Bul. 505] The Snowy Tree Cricket and Other Insects 15 cloth. The crickets which dropped on the cloth during' and after spraying were carefully picked up and kept under observation for several days for signs of revival. About an hour after spraying the bushes were bent over the cloth and the crickets knocked from them by beating. In this way the number of crickets present in the bushes was determined. Volck, Petrotine, Black Leaf 40, Derrisol, and Evergreen gave no control ; Destruxol gave a kill of about 30 per cent. None of these materials injured the foliage. Tests with Ovicides. — Winter sprays, including proprietary dor- mant oils, and lime-sulfur were applied as ovicides on January 17 and February 19. About one week after spraying, pieces of canes bearing eggs were brought into the laboratory. After the hatching period was passed the canes were carefully dissected. The hatched eggs were represented by egg shells while eggs which had failed to hatch were generally shrunken or molded, and easily distinguishable from the paper-like eggshells. Results of the spraying are given in table 3. TABLE 3 Result's of Dormant Sprays as Ovicides against Oecanthus niveus Material Dilution Application Eggs hatched Eggs dead Per cent dead Dormant soluble 4-100 4-100 4-100 3-100 H pints to 10 feet H pints to 10 feet li pints to 10 feet H pints to 10 feet 97 56 175 48 39 78 35 65 56 34 44.6 Spra-mulsion 38.4 Skalol 27.1 Lime-sulfur 53.8 Untreated 46.5 The high mortality of eggs, both sprayed and unsprayed, was probably due, in part, to the fact that they were kept indoors after the spraying. No control can be attributed to dormant oils, and very little if any to lime-sulfur. This is to be expected on account of the protected position of the egg in the cane. Arsenieals. — The use of arsenic compounds as dusts or sprays was not feasible since the bushes are bearing fruit some time before the last of the eggs are hatched and it would be necessary to treat the bushes while they were bearing. Since Ranaree berries are practically all consumed fresh and are sometimes not washed, the danger from an arsenical residue precludes the use of this material. In an attempt to adapt a non-poisonous or quickly volatile poison, calcium cyanide and nicotine dust were tested. Tests with Cyanide and Nicotine Dusts. — Tests were made with three commercial brands of cyanide dusts containing about 28, 45, 16 University of California — Experiment Station and 53 per cent, respectively, of calcium cyanide. Commercial nico- tine dust containing 3.25 per cent of nicotine was used in all the tests of nicotine dusts. The dusts Avere applied with a rotary hand duster equipped with a fan blower. Preliminary cage tests with these TABLE 4 Field Tests of Calcium Cyanidei and* Nicotine Sulfate Dusts against Oecarrihus niveus Material Nicotine dust Nicotine dust Nicotine dust Nicotine dust 45 per cent cyanide 45 per cent cyanide. 45 per cent cyanide.. 53 per cent cyanide . One-half 45 per cent cyanide and one-half nicotine dust One-half 45 per cent cyanide and one-half nicotine dust One-half 45 per cent cyanide and one-half nicotine dust One-half 45 per cent cyanide and one-half nicotine dust One-half 45 per cent cyanide and one-half nicotine dust One-half 45 per cent cyanide and one-half nicotine dust One-half 45 per cent cyanide and one-half nicotine dust One-half 45 per cent cyanide and one-half nicotine dust One-half 53 per cent cyanide and one-half nicotine dust One-half 53 per cent cyanide and one-half nicotine dust One-half 53 per cent cyanide and one-half nicotine dust Ounces per 15 ft. of row Crickets dropped Beaten off Total alive Total dead Motionless Active 8 25 4 10 19 8 19 4 1 5 19 10 45 11 10 46 3 11 9 U 9 8 283* 30 86 227 9.5 23 6 8 21 16 8 5 19 7 8 8 26 10 18 7 2 11 16 5 40* 3 22 21 5 5 26 3 3 19 10 7.5 46* 3 8 41 8.0 176* 25 76 125 8.5 61* 4 12 53 10 60* 4 14 50 10.0 49* 2 47 10.0 189* 2 37 154 6 28 5 3 7 29 8.0 127 23 12 31 131 10 50 6 5 10 51 Per cent kill 65 5 79.1 82.1 47.3 72.5 43 2 76.4 59.2 48.8 34.5 83.6 62.1 81.5 78.1 95.9 80.5 86.1 80.9 83.6 *This number includes the crickets which were motionless when beaten off. materials against the first instar nymphs resulted in high mortality. These materials were then tested in the field. In each test 15 feet of row was underlaid on either side by strips of black cloth. Ten minutes after dusting the crickets which dropped on the sheets were counted and recorded under "Dropped," in table 4. About 30 min- Bul. 505] The Snowy Tree Cricket and Other Insects 17 utes after dusting- the bushes were bent over the cloths and beaten to dislodge the remaining crickets. These were counted as "Motionless" and "Active" in the table. The "motionless" and "dropped" crick- ets were gathered carefully into a box and kept under observation for six or more hours in order to determine the number which revived. This number, plus the number which was knocked off alive, is recorded in the column "Total alive." These tests were carried out in May and the early part of June when the majority of the crickets were in the first, second, and third instars. Field experience showed that nicotine sulfate and calcium cyanide dusts were much less effective against the fourth and fifth instars and adults. The idea of using cyanide and nicotine dusts was finally abandoned owing to the high costs of material, the difficulty of handling, and the high variation in the rate of kill. At the rate of 10 ounces to 15 feet of row, 300 pounds are used to the acre. At 15 cents a pound the cost of treating one acre would be $45.00, plus the labor of appli- cation. In handling and applying these dusts, or mixtures of them, a respirator must be worn. The writer, working for several days with- out a respirator, began to experience mild pain in the lower part of the lungs. In mixing cyanide and nicotine dusts, a gas was evolved which developed sufficient pressure to blow the lid from the mixing container. This gas was probably hydrogen cyanide generated from the calcium cyanide by a small amount of water in the nicotine dust. The kill obtained varied considerably due to variation in climatic and other conditions. Thus a 10-ounce application of the mixed dusts gave on various days 78.1, 80.5, 83.6, and 95.9 per cent kill. High temperatures and still air undoubtedly greatly increase the effective- ness of these dusts. Only favorable days were selected for these trials but even so the variation in results was so great that these materials had to be abandoned from the control standpoint. A commercial poison bran mash moistened and mixed with molasses was tested in cages. It was neither very attractive nor toxic to the crickets. A modified grasshopper bait was then prepared in the laboratory according to the following formula: 10 ounces bran (dry weight) 1 ounce sodium fluosilicate (dry weight) 2.5 ounces molasses (liquid measure) 5 ounces water (liquid measure) 30 drops amyl acetate This mixture proved very attractive to the crickets in cage tests and gave a high mortality. In the field a small amount of this material 18 University of California — Experiment Station was sprinkled in the tops of the bushes, and at night by the aid of a flashlight many were seen feeding upon it. Poison bait, however, could not be sprinkled on the bushes commercially since some of it is likely to fall into the picking receptables, and eventually be eaten by the consumer. Consequently a test was made in which the bait described above was sprinkled on the ground in the rows of bushes. An area of patch 30 by 40 feet was treated in this manner. Counts made one week after treatment showed a reduction of 10.3 per cent in the number of crickets present. In 1927 preliminary cage and field trials with sodium fluosilicate dust gave very promising results. In one case half an acre was dusted, using 15 pounds of 70 per cent dust with diatomaceous earth as a carrier. Two weeks later an examination of 80 feet of dusted row gave 1 live cricket, while 80 feet of check row gave 40 crickets. In the same year plots were laid out as given in table 5. TABLE 5 Preliminary Trials of Sodium Fluosilicate against Oeeantlius niveus in the FIeld; 1927 Plot No. l 2 (untreated) 3 4 (untreated) Number Per cent of rows sodium 150 ft. fluo- long silicate 11 70 1 2 11 6 Carrier Diatomaceous earth Hydrated lime Pounds dust per acre 51.6 48.16 Dusted Sept. 7 Sept. 7 Live crickets per 42 ft. Sept. 19 3 28 15 204 Oct. 4 246 Plots 1, 2, 3, and 4 were adjacent in the order numbered. It is interesting to note that on September 19, plot 2, which was a single undusted row between plots 1 and 3, showed a control of 86.2 per cent, due no doubt to the drifting of the dust during application and to the movement of crickets from this row into the dusted areas. The counts of live crickets are based on beating one side of the row only ; and are comparative rather than representative of the actual number of crick- ets present. On January 21, 1928, no* eggs could be found in plot 1, while plot 4 averaged nearly 100 eggs to a cane. On May 23, 1928, no nymphs could be found in plot 1, while plot 4 averaged about 11 to a linear foot of row. In 1928 cage tests were made to determine the lowest percentage of sodium fluosilicate which would give a total kill. The data so obtained were highly variable, due to uncontrolled factors. The data Bul. 505] The Snowy Tree Cricket and Other Insects 19 in table 6 were based on 30 crickets in each test, on moderately large plants dusted with 2 grams of dust per plant. The cages covering the plants were 2 feet square and 3 feet high (fig. 5). TABLE 6 Cage Tests of Sodium Fluosilicatei against Oecanthus niveus, Using DlATOMACEOUSI EART'H AS CARRIER Material Sodium fluosilicate, 100 per cent. Sodium fluosilicate, 90 per cent... Sodium fluosilicate, 70 per cent... Sodium fluosilicate, 60 per cent- Sodium fluosilicate, 50 per cent Diatomaceous earth After three days After fi^ Number dead Per cent dead Number dead 30 26 86.6 19 63.3 30 22 73.3 29 25 83.3 30 13 43.3 26 4 13.3 9 Per cent dead 100. 100 96 6 100 86 6 30 Fig. 5. — Cages used in control studies. An untreated cage was established, the data from which were not used because ants invaded the cage and killed a number of the crickets. The diatomaceous earth cage, however, represents about the normal death rate and can be considered a fairly satisfactory check. In the same year sodium fluosilicate was tested further in the field as recorded in table 7. The numbers of crickets recorded in the table do not represent the total number of crickets present in the row counted. They are the numbers of crickets beaten off of one side of the row. In an attempt to determine the relation between the number of crickets beaten off and the number actually present, a given length of row was beaten by the usual method. After all of the crickets which were knocked off and counted had jumped back into the bushes the row was underlaid on both sides with black cloth and dusted heavily with calcium cyanide. 20 University of California — Experiment Station TABLE 7 Field Tests of Sodium Fluosil.icate: against Oecanthus niveus Per cent sodium fluo- silicate Carrier Feet of row Amount used, pounds Pounds per acre Live crickets to 50 feet of row Percentage dead Plot No. Before dusting 7 days after 14 days after 7 days after 14 days after 1 20 Lime 400 2 35.9 112 31 8 72.3 92.8 2 40 Lime 400 1% 31.5 112 31 6 72.3 94.6 3 20 Lime 300 3 72 112 40 7 64.3 93.7 4 40 Lime 400 4 72 112 14 1 87.5 99.1 5 72 8 per cent lime, 20 per cent dia- tomaceous earth 200 3 107.9 112 100 100 6 72 8 per cent lime, 20 per cent dia- tomaceous earth 200 \% 38.2 112 16 85.7 100 7 60 10 per cent lime, 30 per cent dia- tomaceous earth 200 m 67.4 112 6 95.1 100.0 8 70 Diatomaceous earth 200 m 38.2 108 8 92.6 100.0 9 70 Diatomaceous earth 200 2% 102 108 3 97.2 100.0 All of the crickets were thus brought down and counted. Rows counted by beating- averaged 2.47 live crickets to a linear foot, while the same rows counted by dusting with cyanide averaged 6.47 to a foot. Thus, beating exposes 38.2 per cent of the crickets which were present in the bushes examined; and these may be regarded as one- third of the total crickets in the row, since only one-third of the width of the row can be underlaid with cloth, or can be examined by beating. By applying these figures, the 112 crickets in ever 50 feet of row by beating indicates 888 crickets actually present in every 50 feet of row. V On the basis of the findings in 1927, a number of growers dusted commercially in 1928. These commercial applications were observed carefully in several instances and all seemed to give a 100 per cent control. The material used was a dust containing 70 per cent sodium fluosilicate and 30 per cent diatomaceous earth, and was applied at the rate of 50 pounds to the acre. Some injury to the bushes occurred in some of the commercial applications. This damage consisted of a killing, browning and curl- ing of the edges of the leaves, usually leaving the center of the leaf green. No systemic poisoning occurred, since the most severely in- jured plants continued to put forth good leaves and no detrimental effects could be detected the following year. Practically no leaf injury Bul. 505] The Snowy Tree Cricket and Other Insects 21 occurred in the experimental applications, although in some cases the bushes were sprinkled with water before dusting- to simulate dew, and in others were sprinkled after dusting to simulate a light rain. It seems that the injury obtained in the commercial applications was caused by dusting in the late evening or early morning when dew was on the plants, or by dusting very heavily. Most of the growers who did not dust in 1928, dusted in 1929, but no injury to the plants was noticed that season. The question of the toxicity of sodium fluosilicate to human beings was considered when this material was tested as a control measure. Mr. Marcovitch 3 states: ". . . . to man and the higher animals the arsenicals are at least nine times more toxic than sodium fluosilicate. .... Minimum fatal doses of various substances by mouth for mam- mals are about as follows : Sodium fluoride, 0.5 gram per kilo ; sodium fluosilicate, 0.12 gram ; and potassium arsenite, only 14 mg. At these rates the following amounts would be lethal to man .... sodium fluosilicate, 7.2 grams; potassium arsenite, 0.84 gram." A study of the residue of sodium fluosilicate left on the berries at different length of time after dusting was made as recorded in table 8. TABLE 8 Amount of Fluosilicate; Bemaintng on Berries at Various Times after Dusting; 1928 Sample Per cent sodium fluosilicate Pounds used per acre Date dusted Date picked Days after dusting 70 50 July 16 July 18 2 70 50 July 10 July 18 8 70 50 July 5 July 18 13 70 80 June 30 July 18 18 Parts per million, fluorine 4 2 2 Less than .5 Parts per million, sodium fluosilicate 6.6 3 3 3 3 Less than .8 At the rate of 6.6 parts to a million of sodium fluosilicate, it would be necessary to eat 2404 pounds of berries in order to consume 7.2 grams, or the lethal dose estimated by Marcovitch. Notwithstanding its relative safety, however, it is not lawful to market berries with sodium fluosilicate on them. The Ranaree variety bears two crops each year, as shown in the graphs of figure 6. The intercrop period is ideal for dusting, since, (1) all of the eggs within the canes have hatched so that no reinfestation can occur after dusting by continued hatching; (2) none of the crickets have laid 3 Marcovitch, S. Studies on toxicity of fluorine compounds. Tennessee Agr, Exp. Sta. Bul. 139:1-48, pi. 1-2. 1928. 22 University of California — Experiment Station their eggs by this time so that a good control during this period results in reduction of crickets the following year; and (3) production of berries at that time is low. The grower has time for dusting and with- out great loss can allow ten days to elapse after dusting without pick- ing, so as to avoid marketing berries with dust on them. This last point is very important, since it is unlawful to market berries with sodium fluosilicate on them. 1927 1928 1929 3000 2500 i_ ~> c .c^ no o_ -+- u 3 3 3 0) o I 1 *1 <'«0 O Fig. 6. — Raspberry production for the years 1927, 1928, and 1929, based on figures supplied by the Central California Berry Growers Association. The points plotted represent the number of chests produced each week. Note the drop in pro- duction between the first and second crops. In 1929 a study was made of the toxicity of various fluosilicates, to the tree cricket. These tests were carried on in screened cages 2 feet square and 3 feet high. Each cage was set over a raspberry plant after the plant had been closely underlaid with wrapping paper. Each plant was dusted with 2 grams of powder after which 20 crickets w r ere introduced. The dead crickets which dropped on the paper were removed from time to time and the total dead at the end of six days is recorded in table 9. In the above tests diatomaceous earth was used as a carrier when the fluosilicate was diluted. The plants used in these tests were kept under observation for some weeks after the close of the experiment for signs of foliage injury. One month after dusting the injury to the plants dusted with 100 per cent fluosilicates was classified as follows : aluminium and sodium, very slight ; sodium, slight ; mag- nesium, severe ; calcium, none ; barium, none ; diatomaceous earth, none. In the 70 and 50 per cent dusts magnesium - alone produced injury. Buii. 505] The Snowy Tree Cricket and Other Insects 23 TABLE 9 Effect of Different Percentages of Various Fluosilicates on Crickets Caged on Dusted Kaspberry Plants for Six Days Material Sodium fluosilicate Aluminium and sodium fluosilicate Magnesium fluosilicate Calcium fluosilicate Barium fluosilicate Diatomaceous earth Untreated Using 100 per cent dusts Using 70 per cent dusts Using 50 dus Number dead Per cent dead Number dead Per cent dead 90 Number dead 19 18 90 18 20 100 20 100 16 19 95 19 95 9 16 80 16 80 9 20 100 20 100 18 2 10 1 5 1 5 3 15 1 Per cent dead 95 80 45 45 90 The efficiency of a dust may depend to a considerable extent upon the size of the particles. Data on the fineness of the dusts used in the above tests are therefore included. The dusts were sifted for five minutes in a Ro-Tap sifter and the percentage composition of the various grades determined as shown in table 10. One pound of each dust was used in determining fineness. TABLE 10 Kelative Fineness of Various Dusts Used Per cent of dust remaining on Per cent through 200-mesh screen 100-mesh screen 150-mesh screen 200-mesh screen Per cent lost Sodium fluosilicate 1.0 4 5 30 9 6.0 2.0 3.3 7.0 38.4 51.0 6.0 29 6 27.1 20 8 37 26 65.0 60 1 7.6 3 57.0 1.1 Barium fluosilicate 9 1 Magnesium fluosilicate 2.1 Calcium fluosilicate 1 5 Aluminium and sodium fluosilicate 2 SUMMARY OF RECOMMENDATIONS FOR CONTROL OF THE SNOWY TREE CRICKET The snowy tree cricket is best controlled by a dust composed of 70 per cent sodium fluosilicate and 30 per cent diatomaceous earth, applied at the rate of about 50 pounds to the acre, with a rotary fan blower. This treatment can be applied for eight to twelve dollars per acre. The operator should walk down the row, directing the dust into the upper third of the bushes. It is necessary to dust only one side of a row. The dust should be applied in the intercrop period and 24 University of California — Experiment Station no berries should be picked for ten days after dusting- since it is unlaw- ful to market berries with this dust on them. The dust should not be applied in the early morning or evening, or at any time when the plants are wet, since injury may result under those conditions. If properly done, the control need not be repeated the next year but in the second or third year it may be necessary to repeat it. THE BLACK VINE WEEVIL AND THE ROUGH STRAWBERRY WEEVIL The black vine weevil, Brachyrhinus sulcatiis Fabr., was noticed in injurious numbers on raspberries in the Santa Clara Valley about 1926. It increased rapidly and appeared in several widely separated places within the next two years. The adult (fig. 7) is a large brownish-black beetle (10 or 11 mm. in length) with scattered, indis- tinct yellow spots on the back. These insects are wingless and spread through a patch by walking, or by being carried by pickers, et cetera. The adults lay small round eggs on the debris collected about the bases of the canes. These eggs are at first opaque-white, but soon turn a light brown. Specimens kept in the laboratory began ovipositing on June 18. Oviposition was continued steadily by some of the speci- mens until October 8. During this time isolated females laid 243, 296, 390, 502, and 562 eggs, respectively, averaging 398.6 eggs each. Four females which laid throughout the entire period (four and one-half months) laid on the average 3.1 eggs a day. The highest number of eggs laid in one day was 15. Eggs hatched in the laboratory from 7 to 20 days after being laid, with the majority hatching from 9 to 14 days after being deposited. The young larvae burrow into the soil where they feed upon the roots of the raspberry. While still small the larvae appear to prefer the smaller roots, 2 to 4 mm. in diameter ; but when half grown or larger, they are generally found feeding on the larger roots and crown below the surface of the ground. At this time they do severe injury to the plants. In feeding, the bark and cambium are eaten in continu- ous patches. The larvae advance slowly as they feed and frequently girdle the plant near the surface so that it dies. Raspberry plantings have been damaged in this manner to such an extent that they were rendered entirely unprofitable and were plowed out. The young larvae are hairy and brown in color, due to the visible ingested wood. When fully grown (fig. 8) they measure about 13 to 14 mm. in length and are yellowish-white in color. They move a few inches away from the base of the plant and construct a definite pupal Bul. 505] The Snowy Tree Cricket and Other Insects 25 cell. The larval period extends through the entire winter but by February 1 the larvae are nearly all mature and resting in pupal cells. After remaining in the pupal stage about three weeks the adults emerge, during the month of March. By May 1 the weevils are prac- tically all emerged, in normal years. The adults climb into the rasp- Fig. 7. — Adult of the black vine weevil. berry bushes to feed on the foliage and fruit but the damage doue in this manner is very slight. They also spend considerable time in the leaf debris at the bases of the plants. Two types of poison baits as recommended by Mote and Wilcox 4 were tested in the field. One consisted of the following: Bran, 5 pounds ; calcium arsenate, 4 ounces ; water, 2 quarts ; molasses, 1 pint. The second was a proprietary mixture of dried, ground apple pulp and sodium fluosilicate, sold under the trade name "Go West." The 4 Mote, D. C, and J. Wilcox. The strawberry root-weevils and their control in Oregon. Oregon Agr. Exp. Sta. Cir. 70:1-24, pi. 1, fig. 1-7. 1927. 26 University of California — Experiment Station Fig. 8. — Larva of the black vine weevil. Fig. 9. — Adult of the rough strawberry weevil. Bul. 505] "The Snowy Tree Cricket and Other Insects 27 apple pulp bait proved more effective, doubtless due to the fact tnat it was able to attract the weevils from the tops of the bushes to the ground. This material should be applied as soon as nearly all of the weevils have emerged from the soil. The grower can determine this by occasionally turning over a few spadefuls of earth and looking for larvae and pupae, which are very conspicuous because of their large size and white color. The time of application should be about May 1. About 75 pounds to the acre should be scattered by hand along the center of the row. Care should be taken not to apply this material to the tops of the bushes where it may get into the baskets with the berries. This control method has been used commercially for one year with very good results. The rough strawberry weevil, Brachi/7'hinus rugosostriatus Goeze, occurred in one localized area in the valley in 1928 (fig. 9). It is smaller than B. sulcatus, being about 6 or 7 mm. long and lighter brown in color. The life cycle is very similar to that of the black vine weevil. The adults emerge from pupae in the field about two weeks later than the larger species. Control measures are the same for both. THE STRAWBERRY ROOT WORM The strawberry root worm, Paria canella var. quadrinotata (Say), is a small beetle measuring about 3 mm. in length having pale brown elytra with four very irregular black spots. The thorax is blackish; the legs are amber. The eggs (fig. 10) which are yellowish and elon- gated, are deposited in groups and protected by a wall constructed probably of fecal material, usually between two closely pressed sur- faces such as fallen leaves and the like. Oviposition in the berry patches continues from about the middle of March until the middle of June, at which time the overwintered adults are nearly all dead. The average number of eggs obtained from each female according to Weigel 5 was 135, and the length of the egg period varied from 7 to 18 days in the greenhouse, but would probably be somewhat longer in the field. The larvae burrow into the ground immediately after hatching and feed on the smaller roots. The outer bark and cambium are eaten and in heavy infestations, plants are considerably weakened by the loss of these roots. The larvae are white ; and while young, and feeding, they show a dark reddish brown stripe down the back due to the presence of ingested bark. The mature larvae are white, with- 5 Weigel, C. A. The strawberry rootworm, a new pest on greenhouse roses. U. S. Dept. Agr. Dept. Bul. 1357:1-48, fig. 1-16. 1926. 28 University of California — Experiment Station Fig. 10. — (a) Eggs of strawberry root worm laid on dried receptacle of rasp- berry. (b) Eggs laid between decayed leaf and glass plate in the laboratory. Note the black wall of the egg cell, (c) Larvae and pupae. The dark stripe on the smaller larvae is due to food, (d) Adult. Bul. 505] The Snowy Tree Cricket and Other Insects 29 out dark coloring except for the head, which is brown. They are curved in shape with the anterior and posterior ends slightly enlarged. The first pupae were taken in the field on June 25 ; they were abundant through July, and had practically all given rise to adults by the end of August. The first adults of the new brood were taken in the field on July 13, whereas the last adults of the preceding gene- ration were taken on June 21. Thus, there is a short period of the year when no adults occur in the field. The newly emerged adults become very numerous in the fall. They feed in the late afternoon and evening on the leaves of the raspberry, and in heavy infestations Fig. 11. — Damage by strawberry root worm to raspberry leaves. reduce all of the leaves completely to lacework (fig. 11). These leaves then dry and drop, whereupon the adults turn their attention to the canes and eat the outer bark which remains green near the base. With the appearance of cold weather in the late fall the beetles go into hibernation in the loose surface soil and debris among the crowns of the plants. No eggs are laid prior to hibernation. In an average infestation 370 adults were gathered up in the surface debris from an area 3 feet square, on February 7. The overwintering adults become active in the early spring with the bursting of the first buds. As soon as the green leaf tips project beyond the bud scales the beetles begin to feed upon them. Frequently every bud on a cane has one to several beetles feeding upon it. In some localities every bud is destroyed so that nothing but the bare canes remain. The injury by this species is fourfold: (1) defoliation 30 University of California — Experiment Station of the canes in the late summer; (2) barking of the canes in the late fall; (3) destruction of the opening buds in the spring; and (4) injury to the smaller roots by the larvae through the summer. No natural checks were discovered which played an important role in the control of this pest. No parasites were reared. The only cul- tural practice which might aid in the control would be the removal of dead leaves and debris from the bases of the plants in midwinter, and burning with the overwintering adults contained therein. Due to the dense growths of canes in the row this practice is hardly prac- ticable and has not been tested in this investigation. Various sprays and dusts were tested. Bordeaux mixture tested in the field in October failed to show any repellent action. Basic lead arsenate as a spray failed to kill this insect in the field in March. Cage tests of poison baits using beet pulp, apple pulp, and bran as carriers for sodium fluosilicate and white arsenic were ineffective. In cage tests beetles fed upon raspberry leaves, which had been dipped in 1 per cent corrosive sublimate solution, were not killed. One grower sprayed with undiluted kerosene, obtaining a fairly good kill of the beetles. About two months later his plants died. This was believed to be due to the kerosene. Experimentally it was found that kerosene sprayed on the ground around the base of the plant was fatal to it; while frequently the plants in which only the tops were sprayed, recovered. In September a cage test was carried out with actively feeding adult Paria, placing them in petri dishes dusted with various materials as shown in table 11. Hydrated lime was used as a carrier. TABLE 11 COMPARATIVE EFFECTIVENESS OF VARIOUS DUSTS AGAINST Paria canella Number of beetles used Three days after dusting Four days after dusting Dusts used Number dead Per cent dead Number dead Per cent dead Basic arsenate of lead 7 7 7 7 7 7 5 4 6 6 3 71 4 57.1 85 7 85.7 42.8 7 4 7 6 5 100 Acid arsenate of lead 57 1 100 per cent sodium fluosilicate 100 70 per cent sodium fluosilicate 85.7 100 per cent hydrated lime 71 4 Untreated In the same manner various concentrations of sodium fluosilicate using talc as a carrier were tested as shown in table 12. Bul, 505] The Snowy Tree Cricket and Other Insects 31 TABLE 12 Effect of Sodium FluO'Silicatei on Paria canella Number of beetles Two days after dusting Three days after dusting Dusts used Number dead Per cent dead Number dead Per cent dead 100 per cent sodium fluosilicate 90 per cent sodium fluosilicate 80 per cent sodium fluosilicate 16 31 26 26 17 29 19 27 16 23 26 26 17 29 2 100 74 100 100 100 100 10.5 16 31 26 26 17 29 6 100 100 100 70 per cent sodium fluosilicate 100 CO per cent sodium fluosilicate 100 50 per cent sodium fluosilicate 100 Talc 31.6 Untreated Inasmuch as these beetles spend the greater part of the day on the ground hiding in dead leaves, under clods, et cetera, an area of berry patch was dusted by applying 70 per cent sodium fluosilicate to the ground only. No control was obtained. The effectiveness of multiple applications was tested in the field as shown in table 13. TABLE 13 Field Tests of 70 Per Cent Sodium Fluosilicate against Paria canella; 1928 Date dusted Dust used per acre, pounds Live beetles per 20 ft. of row by beating Before dusting Sept. 7 Sept. 18 Sept. 27 Oct. 9 21 Plot 1 Aug. 27 Sept. 7 Sept. 18 Sept. 27 135 87.8 100 75 4 4 56 Plot 2 Sept. 7 Sept. 18 Sept. 27 88 100 75 9 yj 145 Plot 3 Sept. 18 Sept. 27. 100 75 21 108 Plot 4 Sept. 27 75 4 In the table the counts labeled "Before dusting" can be regarded as checks on previous dustings inasmuch as the plots were contiguous. Thus the 145 beetles in plot 3, before dusting, were counted at the same time that only 9 were found in plot 2, and 4 in plot 1. From 32 University of California — Experiment Station these results it would seem that two applications of a 70 per cent sodium fluosilicate dust, with diatomaceous earth as a carrier, applied ten days apart, at the rate of about 100 pounds to the acre in the fall, before any of the beetles have gone into hibernation, will give a good control of this insect. The bushes are producing berries at this time and if the grower dusts he must not pick for at least ten days after each dusting in order to allow dusted berries to ripen and drop off. This will mean a loss of 20 picking days. The grower can, in heavy infestations, easily afford to sacrifice this fruit in order to save his patch from destruction. THE STRAWBERRY CROWN MOTH The strawberry crown moth, Synanthedon bibionipennis Bdv., is occasionally a serious pest of raspberries. The eggs are deposited on the lower green leaves, and green canes of the bushes. They are dark reddish brown ; in dorsal view, oval, measuring 0.5 by 0.4 mm., and have a slightly depressed area on the upper side. According to Mote, et al, 6 the eggs are laid from the middle of June until the middle of August. Of several females isolated in jars at San Jose the two most prolific laid 239 and 211 eggs respectively. Six females averaged 51% eggs each in 24 hours. The eggs hatch in about two weeks and the young larvae burrow into the soil a few inches and begin feeding on the roots of the raspberry. The larvae (fig. 12) bore into the main roots excreting reddish pellets of excrement, often held together by silk spun from the mouth. From one to five larvae may occur in a single plant, and in some cases the entire plant is killed as a result of girdling of the roots near the surface of the soil. The injury to the plant becomes apparent at any time during the summer, when a cane or group of canes may suddenly wilt and die. Examination of such canes usually reveals one or more of these larvae in the roots. The larvae overwinter in their burrows in the roots of the rasp- berry and pupate in the spring in silken pupa cases. The adults are about 12 mm. in length and in general appearance somewhat resemble a wasp. The forewings are dark while the hind- wings are membranous. The body is black with yellow markings. The first adults were seen on May 7. At this time many larvae were still immature and from these, adults continued to emerge until August. The last adult was captured in the field on August 27. '• Mote, D. C, J. Wilcox, and O. A. Hills. The strawberry crown-moth in Oregon. Jour. Econ. Ent. 22:936-943. 1929. Bul. 505] The Snowy Tree Cricket and Other Insects 33 Fig. 12. — Larva of the strawberry crown moth, in burrow in raspberry crown. THE RASPBERRY CROWN BORER The raspberry crown borer, Bembecia marginata (Harris), is occasionally found on raspberries in the Santa Clara Valley. This insect is similar to the strawberry crown moth but considerably larger, and the adults are lighter in color, being brown rather than black. No satisfactory control is known for these insects. Flooding 7 and tobacco dust fumigation 8 have been recommended but are not appli- cable to the type of culture employed. 7 Klee, W. G. Strawberry root borer. Third Bien. Eept. St. Bd. Hort., pp. 243-244, fig. 5-7. 1888. 8 Headlee, T. J., and C. Ilg. Some facts relative to the raspberry crown borer. Jour. Econ. Ent. 19:471-477. 1926. 34 University of California — Experiment Station THE RED SPIDER The common red spider, Tetranychus telarius (Linn.), frequently becomes very numerous in raspberry patches in the latter part of August and September. Affected leaves show the characteristic mot- tling, and later die and turn brown while still attached to the canes. The berry patch, under heavy red spider attack, appears as though scorched by fire. Mr. J. F. Landman 9 recommends spraying with a 2 per cent emulsion of light refined oil. A thorough application especially on the undersides of the leaves is necessary for a satis- factory control. THE BLUE SHARPSHOOTER The blue sharpshooter, Cicadella circellata (Baker), in the adult condition (fig. 13) is an elongated insect about 6 mm. in length with a compact body. It is bluish-green in color, with yellow legs, and has yellow marks on the head and thorax. The small white ovoid eggs are inserted into the plant tissue. The nymphs pass through a number of instars but remain pure white until they become adults. The nymphs are active sind can jump considerable distances. The adults are winged and fly rather well. The adults appear on the raspberry bushes about the middle of February and lay their eggs in the green succulent terminal growth, chiefly in the petioles of developing leaves (fig. 14). The young nymphs feed on the tender new growth, keeping mostly on the under- sides of the leaves. When about half grown they feed generally on the upper part of the cane in the shade of the terminal cluster of unfolding leaves. The nymphs reach their maximum numbers about the first of July. At this time the overwintered adults are all dead and the adults of the new brood are just beginning to appear. Attempts were made to obtain a second generation from the new adults by caging them on raspberry plants and on certain wild host plants but no young were obtained. In the field, however, some young nymphs were collected on Malva sp., on October 15, so there is evidently a very slight second brood each year. This insect occurs in enormous numbers in the berry patches. By dusting a row with calcium cyanide and counting the number of sharp- shooters which dropped on to sheets it was found that 1,414 of them occurred in 15 feet of row. The abundance of these insects causes 9 Personal communication. Buii. 505] The Snowy Tree Cricket and Other Insects 35 Fig. 13. — Adult blue sharpshooter. Fig. 14. — Egg punctures and hatching scars of the blue sharpshooter in raspberry terminal. 36 University of California — Experiment Station great alarm to many growers who feel that they must be doing con- siderable damage. In order to determine the damage resulting to the bushes from heavy infestations of sharpshooters, fifteen plants were grown in pots, and from 1 to 270 insects were placed on them in cages. The plants used were small, being about 10 to 12 inches tall, and having 10 to 15 leaves. No damage could be detected to any of the plants so treated. The sharpshooters apparently insert their mouth- parts into the water conducting vessels of the plant and feed largely on the dissolved material from the roots. The plant seems to be able to supply enough of such material for large numbers of these insects, and for its own growth, at the same time. It may be, however, that heavy infestations of this species may reduce the size or number of berries produced, but such was not observed in the field. In the control tests against the snowy tree cricket using calcium cyanide and nicotine dusts, observations were made as to their effect on the sharpshooter. While both of these materials gave a control, the 45 per cent calcium C} anide was found to be superior to nicotine dust, at the same rate of application. In order to give satisfactory control 45 per cent calcium cyanide dust should be applied during the hottest part of still days at the rate of 300 pounds to the acre. Because the damage which even enormous numbers of these insects produced is so slight, it is doubtful if control measures are worth while. FULLERS ROSE WEEVIL Fuller's rose weevil, Pantomorus godmani (Crotch) (fig. 15), in its larval stages, has been so destructive to the raspberry root system that whole patches have been rendered entirely unprofitable and had to be plowed out. The larvae of this insect resemble those of Brachy- rhinus and can be distinguished from them by the fact that the head is somewhat drawn into the body and is whitish rather than brown, as is the case with the Brachyrliinus larvae. An attempt was made to control this insect with carbon bisulfide emulsion as developed by the Japanese beetle laboratory, in New Jersey. One pint to 40 feet was poured into the irrigating ditches full of water, on both sides of a row. No kill was observed. The emulsion was then drilled into the ground 6 inches deep and 1 ounce to a hole. This application killed for a radius of about 5 inches. No satisfactory control measure is known for this insect, on raspberries. Bul, 505] The Snowy Tree Cricket and Other Insects 37 Fig. 15. — Adult Fuller's rose weevil. THE RASPBERRY HORNTAIL The raspberry horntail, Hartigia cressoni (Kirby), has not been sufficiently numerous within the last few years to render it of any economic importance. The adults are slender, wasp-like, black and yellow insects measuring about 14 mm. in length. The eggs are laid Fig. 16. — Mature larva of the raspberry horntail in burrow in raspberry cane. at the tips of the new shoots and the young larvae first spiral down- ward through the cambium, causing the terminals to wilt and droop. The larvae then enter the pith channel (fig. 16) and burrow down the cane. Pupation occurs within the larval burrow. Essig. 10 recom- mends the topping of the infested canes in the spring, and the removal of the old infested canes during the winter pruning. io Essig, E. O. The raspberry horntail. Mo. Bul. St. Comm. Hort. 1:889-901. 1912. 38 University of California — Experiment Station THE CALIFORNIA TREE CRICKET The California tree cricket, Oecanthus calif amicus Saussure, occa- sionally is encountered in berry patches but rarely in sufficient numbers to be injurious. The adults of this species are brown, with darker brown mottling on the wings. The nymphs have a purple stripe down the back. The eggs are laid in two groups through a single hole, one group being up the cane from the ovipositional punc- ture, and the other down. Four to six eggs are thus placed in one group. The control for this species is the same as that for 0. niveus. ACKNOWLEDGMENTS The author wishes to acknowledge the assistance given by Prof. W. B. Herms, Prof. E. O. Essig, and Dr. B. A. Rudolph for many helpful suggestions, criticisms, and aid in procuring equipment. Credit is due Mr. O. H. Lovell and Mr. E. Goldsmith for certain obser- vations on the snowy tree cricket. Mr. E. H. Haack, manager of the Central California Berry Growers Association, has been especially helpful in making arrangements for field work. Mr. R. E. Snell, Mr. Karlburg, Mr. King, and other growers generously donated por- tions of their berry patches for control tests. STATION PUBLICATIONS AVAILABLE FOB FREE DISTRIBUTION BULLETINS No. No. 253. Irrigation and Soil Conditions in the 415. Sierra Nevada Foothills, California. 416. 263. Size Grades for Ripe Olives. 277. Sudan Grass. 418. 279. Irrigation of Rice in California. 283. The Olive Insects of California. 419. 304. A Study of the Effects of Freezes on Citrus in California. 420. 310. Plum Pollination. 331. Phylloxera-resistant Stocks. 421. 335. Cocoanut Meal as a Feed for Dairy 423. Cows and Other Livestock. 343. Cheese Pests and Their Control. 425^ 344. Cold Storage as an Aid to the Market- 426~ ing of Plums, a Progress Report. 427. 347. The Control of Red Spiders in Decid- uous Orchards. 428. 348. Pruning Young Olive Trees. 349. A Study of Sidedraft and Tractor Hitches. 431. 357. A Self-Mixing Dusting Machine for Applying Dry Insecticides and Fun- 432. gicides. 361. Preliminary Yield Tables for Second- 433. Growth Redwood. 362. Dust and the Tractor Engine. 363. The Pruning of Citrus Trees in Cali> 434. fornia. 364. Fungicidal Dusts for the Control of 435. Bunt. 366. Turkish Tobacco Culture, Curing, and Marketing. 436. 368. Bacterial Decomposition of Olives During Pickling. 438. 369. Comparison of Woods for Butter Boxes. 370. Factors Influencing the Development 439. of Internal Browning of the Yellow Newtown Apple. 371. The Relative Cost of Yarding Small and Large Timber. 373. Pear Pollination. 440. 374. A Survey of Orchard Practices in the Citrus Industry of Southern Cali- fornia. 444. 379. Walnut Culture in California. 386. Pruning Bearing Deciduous Fruit 445. Trees. 388. The Principles and Practice of Sun- 446. Drying Fruit. 447. 389. Berseem or Egyptian Clover. 390. Harvesting and Packing Grapes in 448. California. 391. Machines for Coating Seed Wheat with 449. Copper Carbonate Dust. 392. Fruit Juice Concentrates. 450. 393. Crop Sequences at Davis. 394. I. Cereal Hay Production in California. II. Feeding Trials with Cereal Hays. 451. 396. The Mat Bean, Phaseolus Aconitifolius. 404. The Dehydration of Prunes. 405. Citrus Culture in Central California. 452. 406. Stationary Spray Plants in California. 454. 407. Yield, Stand, and Volume Tables for White Fir in the California Pine 455. Region. 408. Alternaria Rot of Lemons. 456. 409. The Digestibility of Certain Fruit By- products as Determined for Rumi- 458. nants. Part I. Dried Orange Pulp and Raisin Pulp. 459. 410. Factors Influencing the Quality of Fresh Asparagus After it is Harvested. 460. 412. A Study of the Relative Value of Cer- tain Root Crops and Salmon Oil as 462. Sources of Vitamin A for Poultry. 464. 414. Planting and Thinning Distances for Deciduous Fruit Trees. 465. The Tractor on California Farms. Culture of the Oriental Persimmon in California. A Study of Various Rations for Fin- ishing Range Calves as Baby Beeves. Economic Aspects of the Cantaloupe Industry. Rice and Rice By-Products as Feeds for Fattening Swine. Beef Cattle Feeding Trials, 1921-24. Apricots (Series on California Crops and Prices). Apple Growing in California. Apple Pollination Studies in California. The Value of Orange Pulp for Milk Production. The Relation of Maturity of California Plums to Shipping and Dessert Quality. Raisin By-Products and Bean Screen- ings as Feeds for Fattening Lambs. Some Economic Problems Involved in the Pooling of Fruit. Power Requirements of Electrically Driven Dairy Manufacturing Equip- ment. Investigations on the Use of Fruits in Ice Cream and Ices. The Problem of Securing Closer Rela- tionship between Agricultural Devel- opment and Irrigation Construction. I. The Kadota Fig. II. The Kadota Fig Products. Grafting Affinities with Special Refer- ence to Plums. The Digestibility of Certain Fruit By- Products as Determined for Rumi- nants. Part II. Dried Pineapple Pulp, Dried Lemon Pulp, and Dried Olive Pulp. The Feeding Value of Raisins and Dairy By-Produces for Growing and Fattening Swine. Beans (Series on California Crops and Prices). Economic Aspects of the Apple In- dustry. The Asparagus Industry in California. A Method of Determining the Clean Weights of Individual Fleeces of Wool. Farmers' Purchase Agreement for Deep Well Pumps. Economic Aspects of the Watermelon Industry. Irrigation Investigations with Field Crops at Davis, and at Delhi, Cali- fornia, 1909-1925. Studies Preliminary to the Establish- ment of a Series of Fertilizer Trials in a Bearing Citrus Grove. Economic Aspects of the Pear Industry. Rice Experiments in Sacramento Val- ley, 1922-1927. Reclamation of the Fresno Type of Black-Alkali Soil. Yield. Stand and Volume Tables for Red Fir in California. Factors Influencing Percentage Calf Crop in Range Herds. Economic Aspects of the Fresh Plum Industry. Lemons (Series on California Crops and Prices). Prune Supply and Price Situation. Drainage in the Sacramento Valley Rice Fields. Curly Top Symptoms of the Sugar Beet. BULLETINS — (Continued) No. No. 466. The Continuous Can Washer for Dairy 484. Plants. 467. Oat Varieties in California. 485. 468. Sterilization of Dairy Utensils with 486. Humidified Hot Air. 469. The Solar Heater. 487. 470. Maturity Standards for Harvesting Bartlett Pears for Eastern Shipment. 488. 471. The Use of Sulfur Dioxide in Shipping Grapes. 489. 472. Adobe Construction. 473. Economic Aspects of the Sheep In- dustry. 474. Factors Affecting the Cost of Tractor 490. Logging in the California Pine Region. 491. 475. Walnut Supply and Price Situation. 477. Improved Methods of Harvesting Grain 492. Sorghum. 493. 478. Feeding and Management of Dairy 494. Calves in California. 495. 479. I. Irrigation Experiments with Peaches in California. II. Canning Quality 496. of Irrigated Peaches. 480. The Use, Value, and Cost of Credit in Agriculture. 497. 481. Utilization of Wild Oat Hay for Fat- tening Yearling Steers. 498. 482. Substitutes for Wooden Breakpins. 500. 483. Utilization of Surplus Prunes. The Effects of Desiccating Winds on Citrus Trees. Drying Cut Fruits. Pullorum Disease (Bacillary White Diarrhea of Chickens). Asparagus (Series on California Crops and Prices). Cherries (Series on California Crops and Prices). Irrigation Water Requirement Studies of Citrus and Avocado Trees in San Diego County, California, 1926 and 1927. Olive Thinning and Other Means of Increasing Size of Olives. Yield, Stand, and Volume Tables for Douglas Fir in California. Berry Thinning of Grapes. Fruit Markets in Eastern Asia. Infectious Bronchitis in Fowls. Milk Cooling on California Dairy Farms. Precooling of Fresh Fruits and Tem- peratures of Refrigerator Cars and Warehouse Rooms. A Study of the Shipment of Fresh Fruits and Vegetables to the Far East. Pickling Green Olives. Dehydration of Grapes. CIRCULARS No. 117. The Selection and Cost of a Small Pumping Plant. 127. House Fumigation. 178. The Packing of Apples in California. 203. Peat as a Manure Substitute. 212. Salvaging Rain-Damaged Prunes. 230. Testing Milk, Cream, and Skim Milk for Butterfat. 232. Harvesting and Handling California Cherries for Eastern Shipment. 239. Harvesting and Handling Apricots and Plums for Eastern Shipment. 240. Harvesting and Handling California Pears for Eastern Shipment. 241. Harvesting and Handling California Peaches for Eastern Shipment. 243. Marmalade Juice and Jelly Juice from Citrus Fruits. 244. Central Wire Bracing for Fruit Trees. 245. Vine Pruning Systems. 248. Some Common Errors in Vine Pruning and Their Remedies. 249. Replacing Missing Vines. 250. Measurement of Irrigation Water on the Farm. 253. Vineyard Plans. 255. Leguminous Plants as Organic Ferti- lizers in California Agriculture. 257. The Small-Seeded Horse Bean (Vicia faba var. minor). 258. Thinning Deciduous Fruits. 259. Pear Byproducts. 261. Sewing Grain Sacks. 262. Cabbage Production in California. 263. Tomato Production in California. 265. Plant Disease and Pest Control. 266. Analyzing the Citrus Orchard by Means of Simple Tree Records. No. 269. 270. 273. 276. 278. 279. 282. 287. 288. 290. 294. 295. 296. 301. 302. 304. 307. 308. 310. 311. 312. 313. 316. 317. 318. 319. 320. An Orchard Brush Burner. A Farm Septic Tank. Saving the Gophered Citrus Tree. Home Canning. Olive Pickling in Mediterranean Countries. The Preparation and Refining of Olive Oil in Southern Europe. Prevention of Insect Attack on Stored Grain. Potato Production in California. Phylloxera Resistant Vineyards. The Tangier Pea. Propagation of Deciduous Fruits. Growing Head Lettuce in California. Control of the California Ground Squirrel. Buckeye Poisoning of the Honey Bee. The Sugar Beet in California. Drainage on the Farm. American Foulbrood and Its Control. Cantaloupe Production in California. The Operation of the Bacteriological Laboratory for Dairy Plants. The Improvement of Quality in Figs. Principles Governing the Choice, Oper- ation, and Care of Small Irrigation Pumping Plants. Fruit Juices and Fruit Juice Beverages. Electrical Statistics for California Farms. Fertilizer Problems and Analysis of Soils in California. Termites and Termite Damage. Pasteurizing Milk for Calf Feeding. Preservation of Fruits and Vegetables by Freezing Storage. 13m-l,'31