AGRIC, DEPT, ENTOMOLOGY I IRPflRY SCALE INSECTS ON DECIDUOUS AND ORNAMENTAL TREES. S. F. CHAPIN, M. D. \\ Vice-President of State Board ,>/' Horticultural Commissioners A REPORT TO THE STATE BOARD OF HORTICULTURAL COMMISSIONERS. [Reprinted for the- Author from the PACIFIC Hi \\\\. I'KKSS of e made to this orchard. The Assessor's roll for 1881 re- ports in this county 335,537 bearing trees of the apple, pear, plum and peach. This does not include the large number of trees which have been destroyed and are unfruitful; neither the immense number of young trees that have been planted, but not yet paying; and, as observed, it leaves out the large number of other varie- ties, cherries, a] moms, apricots, etc., in bearing, which, it is estimated, would make a grand total of 1,000,000 trees. Should the losses ex- perienced by the orchardists now suffering be carried out to all, you can readily estimate the astounding result. The value of the Santa Clara county fruit crop for 1880 was returned at $976,475, notwithstanding the immense losses incurred. The sworn statement of the Assessor, now before rne, says "That all fruit trees in Santa Clara county are assessed as im- provements at the following prices: Trees in full bearing, free from scale, $1.50 per tree; trees bearing, affected with scale, from .00 to 50 cts. per tree, and that there is a large num- ber of orchards situated east and northeast from the city of San Jose, badly infested with scale (and after naming some, say?), and in conse- quence are assessed at .00 to 50 cts. per tree." From this it will be seen that the revenue de- rived from taxation is seriously affected by the presence of this pest upon our orchard trees. The Assessor's roll for 1882 gi^es of the four varieties of trees named above apples, peaches, pears and plums bearing trees subject to tax- ation 280,347, a deduction from the previous year's assessment of 55,190 trees. This loss is in fact upon apple, plum and peach trees, as the young pear trees coming into bearing, and be- ing assessed for the first time, more than equal the loss on that variety. So it is seen that the loss in assessed value on these three kinds of trees totally destroyed has amounted in the one year to $82,785. This is actually but a small part of the loss, as other varieties of trees des- troyed, and the losses of previous years from the scale as well as the reduced value of trees affected but still bearing, cannot well be enu- merated. These trees were destroyed before the application of proper remedies; now, how- ever, from the knowledge of correct treatment, these losses will soon cease, and the taxable property of the county be immensely in- creased. I feel assured that the next assess- ment will show a decided improvement. Thus the magnitude of this evil becomes apparent, and the problem to be solved is of vast impor- tance. Description of this Pest. From the study we have given to this scale during the past three years it may be briefly described as follows: The scale insect is massed upon the bark of the tree and fruit as well, the scale of a dark gray or blackish and tough ma- terial which covers the insect being very small and round in shape over the female, while that covering the male is much smaller and elongated on one side. In both, the higher and central portion of the scale has a yellowish color, and directly under which may be found the insect itself, which is soft and delicate in structure and of a pale straw color. There is no con- nection between the cover and the insect, which is merely protected by it from harm. The shell- I like scale is formed by either the cast-off skins i of the larva or by a waxy secretion of the body j of the insect. The microscope shows the young i female insect oval in shape and flattened. At first it is very small and hardly perceptible to the naked eye, but careful observation will de- tect it as a minute yellow dot on the bark of the tree, crawling about with the six legs with which it is provided, and seeking a favorable locality upon which to fix itself for life. It will crawl about for only a day or two, and then fastens itself to the bark by a beak-like pro- tuberance which it inserts, and procures nour- ishment from juices of the tree. Immediately upon fixing itself it begins to be covered with a silvery material, which, as it grows older, is gradually changed in color to a very dark hue, and enlarges to the size of about one-sixteenth of an inch in dia.neter. The insect soon after fixing itself loses its legs and antennce, and thus remains through life, keeping its flattened shape but growing wrinkled and almost round, gradu- ally increasing in size to perhaps one-sixteenth of an inch in width and one-fifteenth of an inch in length when full of young. After the young emerge it is dried up and disappears. We have counted from the female, when full of young, be- tween 50 and 60 of the minute sacks which con- tain the young perfectly formed insects ready to crawl about. The young male insect is pro- duced in the same manner and at the same time, though not in such numbers; perhaps half a dozen males to a hundred females. In size the male is about one -third that of the female, and in shape very different, being elongated and more angular, provided with six legs placed differently up on the body, with two antennae and two eyes, and with a teat-like protuberance at the rear end of the body ending with a point. At this stage of its existence the male has no wings, and it cannot be discerned without the aid of a magnifying glass. The color of the young male is not a yellow, but of a steej-like or whitish hue It crawls about and fixes it- self upon the bark, as does the young female, and becomes covered with a scale in the same manner, but which is elongated upon one side, and not more than one-half the size of the scale of the female. The male, after remaining its allotted tim'e in the pupa state, emerges as a fully developed insect, having eyes, antenne, six legs and one pair of very long wings of a reddish and transparent appearance, and the protuberance at the rear end of the body is developed into a very long tapering point, nearly as long as the body it- self. The perfect winged male is so minute it can with great difficulty be discerned by the naked eye, crawling and flying about in search of the female, which it impregnates under the scale and then, having fulfilled its mission, it dies. In the season of 1880 we saw the winged males first appear on March 23 i, and in great numbers for a few days. The first brood of young scales appeared the latter part of April. Oa June 27th we found the males from the first brood under the scales and nearly developed with appendages and wing pads, and on July 2d large numbers of them flying about; also as late as July 25fch, and still later, on August 2d, a few were seen. On July 23d the trees were covered with the young of the second brood; August 2d the young males of the second brood were found crawling about. Bark scraped clean on the 23d of July was found on the 25th alive with young insects, and some of them already commencing to be covered with scale. As it was expected at the time these observations were made, a third brood would appear about October, so we found it. On October 17th we found the male scale insect in the first pupa stage of development in the winged form, and also on the same day found the perfect winged insect of the third brood moving about on the tree. These facts prove conclusively that there are three distinct broods of these insects in the sea- son, the earliest portion of the first brood about March 23d, of the second brood about July 2d, and of the third brood about October 17th, there being apparently an interval of 14 to 15 weeks between the different broods of the season. The young female insects were found crawling about through the season and as late as the last of November. The last brood remains through the winter under the scale until the approach of warm weather in the spring, when they again ap- pear. While the Aspidiotus Conchiformis will de- velop but one or at most two broods per season, this new species of Aspidiotus will produce three broods, and each female probably 50 young. This present season of 1882 has been in the de- velopment of fruit and insects about three weeks or more later, consequently the appearance of the scale was not expected as early as last year. The first winged male scale insects of this species were discovered this year on April 25fch crawling about on an English hawthorn tree. At that time no young female scale insects were to be found, but the old females under the scales were approaching maturity, and in due time the young appeared. Foes of Scale Insects. The natural enemies of the scale insect are the larvae of some varieties of the Coccinellidce, or lady-birds. The season of 1881 developed in great num- bers an important enemy of the scale, viz. : the Chrysopa or lace-winged fly, the larvae of which prey upon it. This is a beautiful, slender and delicate fly, bright green in color, with large golden eyes, and very long wings like lace. The eggs are very minute, white and oval in shape, and are attached by a long and slender pedicle to the underside of leaves or the fruit. The larva is about one- quarter of an inch long, slender, and tapering from the middle toward both ends. It is provided with jaws, each per- forated, through which it sucks the juice of its victim. Remedies for Scale Insects. In 1881 Mr. J. H. M. Townsend, of the Santa Clara County Horticultural Society, kindly placed at our disposal a large number of trees infested with scale for the use of the committee in making such experiments as were desired. A series of careful experiments for the destruc- tion of the scale pest were made and the results carefully noted. "Other experiments had been under way in our own orchards for many months. These exprimenta demonstrated on one hand the inefficiency of many applications, and on the other hand showed a certain means for the destruction of the scale insect. The remedies which have proven successful will destroy all the varieties of scale, as the one under treat- ment is the most difficult of all to overcome. A portion of these experiments are numbered, and the results obtained, stated as observed, at different dates up to this time, October, 1882, No. 1. Concentrated lye of the American Lye Co., one pound; water, two gallons. Feb- ruary 22, 1881 Applied by spray upon two peach trees infected by scale; washed in the afternoon when the trees were dry; effect, scale killed ; the tenderest wood was killed also. July 5, 1881 New wood grown over the trees four and five feet long. No. 2. Concentrated lye, one pound; water, two gallons. March 10, 1881 Applied by spray upon two peach trees infested by scale, washed in the morning when the trees were damp with dew. July 5, 1881 Scale killed; buds and twigs not injured; fruit abundant and trees most healthy. No. 3. Concentrated lye, one and one-half pounds; water, one gallon. June 23, 1881 Ap- plied by pouring from a dipper upon two pear trees infested with scale and with numerous limbs dead. Lye so strong as to burn bark and foliage. August 2, 1881 Scale entirely des- stroyed; bark being restored and new foliage appearing. No. 4. Concentrated lye, one pound; water, one gallon. July 5, 1881 Applied by spray upon a large apple tree badly infested by scale; bark and leaves burned. August 2, 1881 Scale killed; green layer of bark being rapidly re- stored and new leaves and blossoms appearing all over the tree. The foregoing trees have since been mostly killed by the application of a low grade of coal oil. No. 5. Concentrated lye, one pound; water, one gallon. February, 1881 One almond tree, one Easter Beurre pear tree and two apple trees, grafted, were washed by brush with this strength of lye in order to destroy the red spider and its eggs, which could not be de- stroyed by previous applications of lye, one pound to five gallons, and also one pound to three gallons; another and the main reason being to ascertain the effects of very strong lye upon the trees. No scale upon these trees. This application destroyed the red spider and its eggs on these trees so that it did not appear for months; but, however, later on the trees be- came again infested. While the strong lye will destroy a large number of the eggs of the red spider it is found that all cannot be reached. The effect upon the bark and health of these trees was wonderfully good, the bark being very smooth and having a bright green, velvety ap- pearance and totally free from all moss or other parasites. No. 6. Concentrated lye, one pound; water, one gallon. The experiments in this number were made upon a section of orchard in a square block comprising 357 Ickworth plum trees, cut down and grafted into Petite prune; some year- ling prune trees having been put in in places and washed as were the plums, of these 126 trees were washed in February, 1881, with the above strong lye, applied with a brush. Among the 357 trees were eight trees badly infested with scale. No others had any scales upon them. The infested trees were scattered about as follows, and washed as indicated: No. 10 in first row and 4 in llth row were washed with lye, one pound to three gallons of water. The effect was not quite sufficient to completely destroy the scale, though so in- jured that they did not breed. Afterward these two trees were washed with one pound to one gallon, and this effectually ended the scale. No. 7 in Cfch row, 10 in 7th row, 11 in 12fch row, 8 in 14th row, 3 in 17th row and 11 in 17ch row were washed with lye, one pound to one gallon of water, with the effect of com- pletely destroying every scale upon them, and not one has appeared upon any of these trees* since that time. These trees have been in the finest possible condition from, the time of this application. Among the trees not washed with the strong lye, two were found, in June, 1882, to have scale upon them; one of these, the top having become badly broken by wind, was dug out and burned, the other was washed soon as discov- ered with the whale-oil soap and sulphur mixt- ure; owing to the foliage upon the tree not every part of it could be touched. Yet, how- ever, the scale was destroyed, so far as could be found. No. 7. Concentrated lye, 1 pound to one and one-half gallons water. Five Bartlett pear trees obtained from the nursery and planted in 1881 and scattered among a considerable number, al- though carefully examined at the time for scale,, were found in June, 1881, to have a few scales upon them. These were at once washed with the above strength of lye, which destroyed the scale completely upon three of those o trees,so that none subsequently appeared. On two of them, however, a live scale or two must have remained on the trunk of the tree at the surface of the ground untouched by the lye, as in September following a few young scales were discovered, located close to the ground. These were again washed in the same manner. Since that wash- ing no scale has been found upon either of these trees until this month (Oct. 16, 1882). On one of them has been found a few young scale. The tree was immediately washed with the whale- oil soap and sulphur mixture. On another Bartlett pear tree, not, however, numbered with the above, was found some scales, Nov. 7, 1881. This tree, being entirely dormant, was washed with lye one pound to one gallon water, com- pletely destroying the scale, as none can be found on it this year. Among the Yellow Egg plum trees, one was found January, 1882, with scale upon it, and washed at once with lye one pound to one gallon water, and repeated in Feb- ruary. No scale were left, as none can ba found at this date. Another Egg plum tree was found infested in June of this year. To this was ap- plied, by a brush, the whale-oil soap and sulphur mixture with some lye added. No scale can now be found upon it. The trees in experiments five, six and seven are in an orchard of 50 acres. I have constantly and carefully watched all these trees, and at this date no scale can be discovered in the en- tire orchard. Should any hereafter appear, the treatment will be by lye one Ib. to one gallon water. With this success in my two years' in- dividual practice, I feel justified in repeating the statement I made at the first State Fruit Growers' Convention, that young orchards can be kept free from the Aspidiotus perniciosus by the right use of concentrated lye as a winter wash, and the whale oil soap and sulphur mix- ture for summer. In the following experiments the trees were all badly infested with scale: 8. Concentrated lye, one and one-half IBs; wa- ter one gallon. June 24, 1881 Applied to two Clairgeau pear trees; brush used in order to save foliage; many limbs dead from effects of scale. Jane 27 Trees burned considerably; scale killed where reached. July 2d Much of the bark showing a healthier appearance. July 23d Trees still better. August 2d No sign of scale; green layer of bark being restored very rapidly; the fruit quite clean, because no scales of second brood were upon it. April 25, 1882 Examined the trees, and found a very healthy top. and with new bark where burned with the lye when washed in the summer. All the sur- face was not touched by the lye, and where not washed the scales still existed. Wherever the bark was washed, owing to the time that it was done, it was cracked across. Yet underneath this cracked surface was found new and healthy bark. October 14, 1882 There has been a good growth of new wood this season, and the under bark has maintained its fresh and healthy appearance over entire tree. 9. Concentrated lye, one and a half K3. ; wa- ter, one gallon. June 24, 1881 Applied on a portion of tree to ascertain the effect upon the stain of bark. July 23i The bark where washed shows much less stain; lighter in color, and the green layer being restored. August 2d Stain rapidly disappearing. 10. Concentrated lye, one fib. ; water, one gal- lon. July 5, 1881 Mixed accurately, and ap- plied same day upon pear tree. July 23d Scale where reached entirely destroyed; bark burned by the lye, but otherwise healthy and good where it was previously sound. April 25, 1882, and October 14, 1882 Observations nearly the same as in the preceding number, the bark under the cracked outer layer being all renewed, and with a bright, healthy, green layer free from stain; free growth of new wood during the season. 11. Concentrated lye, one pound; water, one and one-half gallons. Tree washed same time as above and with about the same results, al- though an unthrifty tree. October 14, 1882 The tree had been pretty well destroyed by the scale last year, and shows but a little growth of new wood. 12. Concentrated lye, one lb.; water, two gallons. Same as above, except that the tree was still more thoroughly ruined by scale, and at this date has not recovered ^but little new wood; what there is, however, being healthy. 13. Concentrated lye, one lt>:; water, three gallons. This tree had been washed by spray- ing April 1, 1881, with this strength of lye, which proved too weak to destroy the scale. July 23, 1881 Young scale insects covered the tree; the tree was left to itself with that wash- ing. April 25, 1882 Observed that the scale was abundant and fast accomplishing the de- struction of the tree. October, 14, 1882 The tree is dead to within one foot of the ground, but from the collar many new sprouts have grown. No. 14. Concentrated lye, 1 lb; water, 5 gals. June 23, 1881 Applied to two trees, one slightly and the other badly infested with scale. This wash was used by pouring it upon the trunk of the trees and allowing it to run down and soak into the ground; the tops of the trees were not touched. This experiment was made, as it had been publicly stated that this weak lye used in this manner was an effectual rem- edy. July 2, 1881 No effect produced upon the scale where not reached by the lye. August 2, 1881 No effect other than no- ticed above; scale only injured where touched by the lye, and second brood of young scale in- sects crawling all over the top of the trees. April 25, 1882 Trunk quite clean and healthy, but the top full of scale insects of the last season alive and approaching maturity. October 14, 1882 Tree covered with scale, old and young; the trunk, however, where washed, appearing far more free than the up- per portion; the bark where washed is healthy. Use of Kerosene. In the following experiments with kerosene, the action of that agent was reported as it then appeared at the date of report, but the subse- quent effects which will now be stated, show how important it is to allow ample time to elapse before coming to a conclusion upon the merits or demerits of a particular proposed remedy. The use of coal oil when the tree is full of sap is plainly shown to be unallowable. These will be detailed as they appeared at the time, and also as seen this season. No. 15. Kerosene, low grade and heavy, 110 test. June 1, 1881 Applied to two pear trees, spraying, with coarse spray used and oil thrown over the entire trees. June 27, 1881 Observed that the foliage had been killed and the trees considerably affected; scale killed. July 2, 1881 New leaf buds coming out. July 23, 1881 New foliage all over the trees, and seem- ingly new vigor throughout; new shoots six inches long; no scale to be found, and the green layer of the birk healthy to all appearance. August 2d Foliage increasing rapidly all over the trees, and, apparently, the trees were gain- ing in health. Thus they appeared up to Au- gust, 1881. The observation of these trees on April 25, 1882, showed a very different state; the trees were dead. No. 16. Kerosene, high grade, 150 test. June 1, 1881 Applied by spray upon two pear trees. June 27, 1881 Observed that the foliage had not been killed, but that the scale had all been destroyed; the trees apparently uninjured. July 2d New leaf buds coming forth. August 2, 1881 Trees appear healthy; foliage unin- jured; scale showing no signs of its presence, and the fruit showing less effects from scale on account of the wash it bad received. April 25, 1882 Trees were dead. No. 17. Kerosene, high grade Diamond brand, 150 test. July 27, 1881 Applied upon two pear trees with a coarse heavy spray over entire trees; trees very badly infested. August 2 Effectually destroyed the scale; the trees and foliage apparently entirely healthy. No per- ceptible effect upon the trees, but completely dryiug up the scales, so that they are blown away by the wind. The fruit is not affected by the kerosene, but the scale upon it is killed, and the fruit is very clean. It is observed that kerosene of 150 test evaporates rapidly, and leaves but little signs of having been applied. April 25, 1882 One tree dead; the other not dead but nearly so. October 14, 1882 Ex- animation showed trees to be dead. No. 18. Kerosene, same brand. July 27, 1881 Applied upon a pear tree by spray atomizer, which produced a very fine mist only. Aug- ust 2, 1881 The same effects produced as in No. 17; scale appeared to be entirely destroyed; no apparent effect upon tree or foliage. April 25, 1S82 Tree not dead, but with many scales upon it. October 14, 1882 Old wood dead, but new wood from near the ground. No. 19. Gasoline. July 27, 1881 Applied upon pear tree by heavy syringe spray thor- oughly over the tree and foliage. August 2, 1881 Not effectual in destroying the scale; too volatile; many of the insects killed, but a large portion unaffected; no apparent effect upon the tree or foliage at that time; on this tree the young male scales just hatched out were found crawling about. April 25, 1882 The tree has been almost killed by the scale infesting it. October 14, 1882 Tree still alive, with some si, to 2 gallons of water. I am glad to say that most nurserymen are desirous to do all in their power to destroy the scale. Among other means of preventing the spread of scale, thorough and constant cultivation of an orchard should be kept up, and one promi- nent difficulty in the way of eradicating the scale I believe to be the practice so prevalent of growing other small crops in the orchard be- tween the trees. It cannot be too strongly impressed upon the mind of every owner of an orchard that he must personally watch his orchard and exercise such constant supervision that no infested tree shall escape observation, and, when found, the proper remedy at once be applied. In the orchard re- ferred to where chance trees have been found infested, no other course would have saved me from the overwhelming spread of the scale. The experiments of 1881 and the subsequent use of lye in instances mentioned, indicate the remedy. This should always be used when the tree is dormant, and when the foliage has dis- appeared from the trees. In our climate that time is the winter, and at any time before the trees put forth their buds. Applying the Lye. The strength of lye should be one It), to one gallon water where trees are infested with scale. Where it is only desired to cleanse the tree from moss one K>. to three or four gallons of water is sufficient. The best method of ap- plying the concentrated lye is by dissolving in boiling water, and throwing it upon the trees with a force pump through 40 or 50 ft. of - jHjl one-half inch rubber hose, to which is at- tached a nozzle, having for its opening a simple straight slit, very narrow in width, and one-sixteenth to one- eighth of an inch long. The best spray tip yet devised is that made at San Jose, called the Merigot Spray Nozzle. The pumps most used for this purpose are the Gould pump and the Merigot pump. The latter is made at San Jose, and is cheaper than the Gould pump. Great care should be taken to cover the tree entirely with the solution of lye, as upon its thorough application depends its success. One of the greatest difficulties in the use of strong materials is from the spray falling upon the person of the operator and burning and injuring the skin. la order to overcome this obstacle, I have devised a simple "exten- sion nozzle" of slight cost which is very light and which may be made of any length desired, say from four to 15 ft., or even longer. By the use of this extension it is" perfectly easy to reach and spray any orchard tree without danger and discomfort. The cost of materials and appa- ratus may be given as follows: The Gould pump costsabout $10 without acces- saries. The Merigot pump $12. The suction hose and the long hose will cost according to quality used, from 15 cents to 25 cents per foot. The Merigot spray tip, if purchased alone, $1.50. If bought with pump, the pump and spray $13. The bamboo extension with globe valve seven ft. long $2.75. All excess in length over seven ft. 25 cents per foot. The concen- trated lye, of the American Lye Co. in one-It) cans by the case of 48 R>3., $3 50 per case. English caustic soda in GOO pouod drums, $33 to $35 per drum. The whale oil soap and sulphur mixture called the "Codlin Moth Wash" is manufactured in San Francisco and the price can be obtained by inquiring of Messrs Allyne & White. In conclusion I will give the analysis made v Prof. Hilgard, of the State University, of a sample can of American Lye Co. concentrated lye. The can sent I took from a lot I had been using, and is supposed to be a fair sample of the manufacture. The analysis is as follows: Caustic potash Caustic soda and carbonate of soda 8.3 91.7 100.0 With this I submit my report, expressing my firm conviction that ere long we shall be freed from the ravages of one of the most dreaded pests known to horticulturists. 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