UNIVERSITY OF CALIFORNIA. 
 
 AGRICULTURAL EXPERIMENT STATION. 
 BERKELEY, CAL. 
 
 E. W. HILGARD, Director. 
 
 BULLETIN No. 116. 
 
 Much enlarged. Length one-tenth inch. 
 
 THE CALIFORNIA VINE HOPPER. 
 
 MAY, 1897. 
 
 miii«iiniT-iiiniT-iimi tmttmmi\t 
 
Digitized by the Internet Archive 
 
 in 2012 with funding from 
 
 University of California, Davis Libraries 
 
 http://www.archive.org/details/californiavineho116wood 
 
THE CALIFORNIA VINE HOPPER. 
 
 By C. W. Woodworth. 
 
 Four things injuring the vineyards in this State may be counted as of 
 the first importance and as doing the greatest amount of injury They 
 are first, the mysterious and fatal Anaheim disease, which has almost 
 stricken from the list of the vine-growing regions of this State a large 
 district around Anaheim and which has entirely baffled the researches 
 of trained investigators, and which does not yield to any known method 
 of treatment. Second, the Phylloxera, which, were it not for the pro- 
 tection available by the use of resistant roots, would, as it threatened to 
 do in Europe, practically annihilate every planting of European vines. 
 Third, the mildew, which is capable of inflicting an immense amount of 
 injury, especially in the moister regions where the production of fruit 
 would be practically impossible if we did not know and use the proper 
 remedy : sulphur. Finally, the vine hopper, which is by no means in- 
 trinsically as injurious as either of the others, but because of its pres- 
 ence almost everywhere, and the absence heretofore of a remedy, has 
 probably done year by year as much injury as any of the others. The 
 Anaheim disease and the Phylloxera threaten the very life of the vine, 
 while the mildew and vine hopper decrease the crop and make it unpro- 
 fitable, which from the standpoint of the farmer is equally as serious a 
 matter. Mildew does its greatest injury in the moister regions and in 
 the spring of the year, while the vine hopper is more serious in the drier 
 regions and in the summer and fall. 
 
 As has been stated above, there has heretofore been no remedy found 
 for the vine hopper, and everything that has been tried has proven use- 
 less. The object of this article is to point out the reasons for the failure 
 of these attempts at treatment, so that others will not waste money in a 
 useless line of experimentation, and to suggest a line of work giving 
 much more promise of results and bidding fair to be a solution of the 
 problem. It will at least be useful to carefully enumerate and discuss 
 the factors in the problem, for the solution of it will mean hundreds of 
 thousands of dollars to the farmers of the State. 
 
There are many important facts in reference to this insect that we are 
 still unacquainted with, and some of the very generally accepted ideas 
 are entirely erroneous. We will first discuss the facts in the life history 
 of the insect and its relation to the grape vine, and then consider the 
 remedies. 
 
 THK HOPPERS IN WINTER. 
 
 This is a point in the life history about which there is the greatest 
 difference of opinion among farmers, and the most erroneous ideas exist. 
 The commonest of these errors we will enumerate and discuss. 
 
 The insect does not pass the winter as an egg. In the spring there is 
 no such a thing as hatching out. Warm weather cannot aid nor cold 
 weather retard their hatching, because they do not hatch at that time 
 of the year. The insect that occurs in the spring is not a young insect. 
 Everything done in the winter with the idea of destroying the eggs is 
 done on a wrong theory, for there are no eggs to destroy at that time. 
 A great deal of time and money has been spent every year in acting on 
 this erroneous theory. 
 
 The i?isect does not pass the winter in the ground, in any form, at least 
 to any extent. The ground would be the last place to look in the winter 
 for living leaf hoppers. The idea probably arose because some other 
 common insects, with an entirely different life history, do pass the 
 winter in the ground (the grasshopper for instance, in the form of 
 masses of eggs), and partly because dead hoppers can often be seen on 
 the ground in the fall in considerable numbers. Whatever is done in 
 the winter to the soil will not have any effect on the hopper. 
 
 The insect does not pass the winter about the vine, in any considerable 
 numbers. Some suppose the bark is full of eggs that hatch in the 
 spring, and others think the insect is hiding beneath it. Both ideas are 
 entirely wrong. On the one hand no eggs pas's the winter, and on the 
 other the insects could be found if they were actually hiding there ; but 
 in truth only an occasional one can be seen. Some scale insects may be 
 killed by spraying the plant in the winter, but the vine hopper is a dif- 
 ferent kind of insect and the money which is spent every winter, some- 
 where, experimenting with the vine hopper, is that much thrown away. 
 
 The insect does not pass the winter in the fallen leaves to any great ex- 
 tent. This is the most wide-spread idea in this State and is based, not 
 on observation, but on statements in books which refer to the eastern 
 insect and the eastern winter, and even there is not strictly true and as 
 regards the condition here is absolutely false. A good many hoppers 
 may be found on the fallen leaves in the fall, but they do not pass the 
 winter there and all that tr}^ to do so die. With our warm winter they 
 must have food. They cannot sleep over winter as they could if it were 
 colder. A few may be found anywhere in the winter even on the dead 
 leaves, but they cannot stay there all winter. Much money has been 
 spent every winter in the destruction of leaves, and those that have tried 
 
— b— 
 
 the experiment have been at a loss to know why they produced no prac- 
 tical results, and have blamed their neighbors for not doing likewise, 
 thinking that the neighbors harbored the insects that attacked them in 
 the spring. 
 
 During the winter the insect leads a somewhat active life, feeding on 
 every variety of plant that is green. They may be found anywhere at 
 any time. Every insect that attacks the vine in the spring has been 
 present in the neighborhood of that vine all winter as an adult active 
 insect. 
 
 Winter is a very critical time in the history of these insects. In the 
 fall they may be found of all ages and sizes, from the egg to the aged 
 perfect insect, but the winter climate is so fatal that all the eggs and 
 young die, and of the adults only the youngest and most vigorous sur- 
 vive. If the winter is more than usually severe, they will be very much 
 reduced in numbers and do but little injury, and that late in the season, 
 when they will have increased sufficiently in numbers. But if on the 
 other hand the winter is favorable to them, as the past winter has been, 
 they will begin in large numbers and, if nothing happens to check them, 
 may do very great damage. 
 
 During their winter life the insects, though somewhat active, are by 
 no means so active as in the summer, and they are therefore much less 
 conspicuous. The injury they do to plants is also very slight. They 
 only take enough food to meet their present needs and the plants they 
 attack generally suffer scarcely at all. During the colder weather they 
 are especially inactive ; many fall from the plants and lie on the ground, 
 and are quite difficult to find. 
 
 While the insects feed on all varieties of plants, they have decided 
 preferences for some, and will be found much more abundantly on such 
 plants. Often toward spring the leaves will show the effects of their 
 attacks by the small paler spots characteristic of the work of insects of 
 this group. 
 
 THE HOPPERS IN SPRING. 
 
 With the coming of the warmer weather in the spring, the needs of 
 the insects increase not only on account of the more active life, during 
 warm weather, but because food must be taken with which to produce 
 their eggs. When the leaf hoppers become adult the sexual organs 
 have scarcely more than begun to develop, and they require a great deal 
 of food for this purpose. Those whose sexual organs had developed 
 considerably in the fall were not able to survive the winter because of 
 that drain on their vitality, and only those in which these organs were 
 not growing, are alive in the spring. These organs with the return of 
 warm weather start to grow, and as this sharpens the appetite of the 
 insects, they become more restless and migratory. As soon as the 
 grape-vines leaf out, they will find the hoppers waiting for them. 
 
How they feed. By carefully examining the under side of the body 
 with a microscope, one will notice between the six legs lying on the 
 breast and projecting backward from the head, a rather thick pointed 
 organ which is capable of being bent out nearly at right angles from the 
 body. This is the proboscis or sucking-tube by means of which the 
 insect obtains its food. The method of inserting it can be observed 
 by lying down under a vine and remaining quiet a little while till the 
 hoppers get accustomed to your presence, when by watching an insect 
 that has alighted in such a position that one gets a side view of it, he 
 may see the whole process. The insect first, by straightening its legs, 
 raises itself from the plant a distance about equal to the length of its 
 proboscis. The proboscis will then be seen to bend down till the tip 
 touches the plant and then the insect draws itself towards the leaf, forc- 
 ing the proboscis in its full depth. The insect comes thus much closer 
 to the leaf than it would ordinarily stand. The food is sucked up 
 through the proboscis, and includes not only the juices of the plant, 
 but also the more solid substances in the cavities of the leaf, the pale 
 spots being due to the removal of the green bodies of the leaf. 
 
 The injury to the pla?its. Whereever the beak is inserted the skin or 
 cuticle of the leaf, which protects the leaf from drying out, is broken 
 and the leaf is that much weakened, or requires that much more water 
 to keep it in healthy condition. Some of the substance of the leaf is 
 also removed and the leaf has less of the green bodies which are essen- 
 tial in the manufacture of the food for the growth of the plant, but these 
 are not as important as the loss of water and the inj ury to the cuticle 
 which makes a continual leakage. The injury from loss of water is 
 twofold ; first, the only condition under which growth is possible, is 
 that the water in the growing part be under tension, that is, that it be 
 supplied faster than it is used, and if the leakage prevents this tension, 
 no growth can take place no matter how much food may be present. 
 Secondly, when the tension is removed the leaf undergoes changes 
 which we call ripening, which finally result in the death and dropping 
 of the leaf. Now every leaf costs the plant something in its production. 
 The leaf is a factory for food, and unless it remains on the plant long 
 enough to manufacture more than it costs it is a loss to the plant. The 
 leaf hopper is a very small insect, and it would require a great number 
 to be as much of a drain on the vine as the production of a berry if, 
 like the fruit, they merely took their food from the plant without other- 
 wise injuring it. But the hopper, while taking nowhere near as much 
 food from the plant as the fruit does, still is able to stop the growth and 
 kill the leaves. It will be seen that this injury is produced only when the 
 loss of water is large enough to seriously reduce the tension. In the 
 drier regions and in the drier part of the year, therefore, the injury is 
 most severe. Under favorable conditions it might amount to nothing. 
 
 There is a special condition in the spring of the year, when an injury 
 occurs of a somewhat different nature. Usually the hoppers do not at- 
 tack seriously the very young leaves, but in the spring, if the vines 
 come out late or the insects are in unusual numbers, or if the weather 
 
— 7— 
 
 is warm, favoring their early and active migration to the vines (all of 
 which conditions occurred this spring), the hoppers may attack the ex- 
 panding leaves and so injure them, especially at the veins, that they 
 never fully expand ; and the leaves ripen very fast and fall before they 
 are hardly replaced by new foliage. In the meantime the first fruit 
 buds appear and, because of this condition of affairs, fail to set fruit. 
 This occurs only early in the spring and not very commonly with this 
 species, but more often in the case of the large leaf hopper that is found 
 along the coast. 
 
 Egg -laying. The eggs begin to be laid by the time the first buds 
 appear and are laid continuously all the rest of the season. At the end 
 of the abdomen of the female there is a spear-like ovipositor concealed 
 between two large plates, which form quite a third of the abdomen. 
 This ovipositor is nearly as long as the proboscis and is inserted into the 
 plant in much the same way and the egg is forced through it into the 
 plant. Eggs are laid only in the soft new growth, on the leaves or 
 stems or tendrils. The insects produce only a single egg at a time, 
 which is relatively large. They continue a long while, producing them 
 certainly till after their children are grown and have begun to lay eggs. 
 There seem to be no data as to the number of eggs produced nor the 
 length of time it takes an egg to hatch. 
 
 The young insects. The young insect on hatching crawls out into the 
 open air and making its way to the nearest leaf takes a position on the 
 under side, preferably near a vein, and leads a very quiet life. It ob- 
 tains its food in the same way as the adult and resembles it in most par- 
 ticulars, but is of course without wings. Though it is capable of jump- 
 ing, it must be disturbed a great deal before it can be made to do so, 
 preferring to run away or to hide next to a vein. This retiring dis- 
 position makes it a very inconspicuous insect. As it grows it goes 
 through a set of moults as do other insects, finally obtaining wings as it 
 becomes adult. The number of moults that the insect passes through 
 has not been determined. The injury done by the insects while young 
 does not seem to be very large as compared with that done by the adult. 
 Their sluggish habits and shorter life requires less, as well as the fact 
 that they have to provide only for their own growth. 
 
 THE HOPPERS IN SUMMER. 
 
 The numbers in the spring gradually increase until practically all the 
 hoppers have left the other plants and accumulated on the vine ; then 
 they gradually decrease as the more feeble ones die, until the beginning 
 of summer when the first brood of young ones begin to reach maturity 
 and augment the numbers. This is about the first of June. From that 
 time on they continue to multiply as long as the season lasts, and at 
 any time the insects can be found in all stages of development. 
 
 The characteristic appearance of the leaf affected by these insects now 
 becomes everywhere apparent. Besides the pale mottlings that have al- 
 ready been mentioned, one may notice, especially on the under side 
 where the insects chiefly stay when not on the wing, many small spots 
 
— 8— 
 
 of all shades from brown to black. These spots are the excrement of 
 this insect. Similar spots are made by other insects of this order and 
 by the true thrips. The worst affected leaves gradually die and fall, 
 making the vines almost bare when they should be dense with leaves. 
 When this condition is produced, the fruit is of an inferior quality. 
 Especially is it lacking in sugar and other solid contents, and therefore 
 dries into small raisins, or makes a thin watery must for wine-making. 
 
 RKMKDIKS. 
 
 Under this head we will treat the various means that have been em- 
 ployed or suggested for preventing or mitigating the injury from leaf 
 hoppers. 
 
 Sheeping the vineyard. This is one of the favorite remedies and is 
 depended on, more because it is supposed that it ought to work than 
 because any one has ever had good results. There is a natural varia- 
 tion from year to year with this as well as with all other insects, and as 
 one is most likely to try a remedy of any kind during or just after a bad 
 season, it is not surprising that there is considerable testimony to the 
 effect that good results follow sheeping. No one who has carefully com- 
 pared adjacent vineyards where sheeping and not sheeping have been 
 employed , will be able to say that there is an appreciable difference in 
 the fields. We are not discussing the merits or demerits of turning 
 sheep in the vineyard to eat off the leaves ; but as far as its effects in 
 reducing the numbers of leaf hoppers, there is not one particle of reliable 
 evidence in its favor. The theories for sheeping are many but all un- 
 tennable. Some hope to destroy the eggs and young, and this in a 
 measure they do accomplish ; but they do not realize the fact that, if 
 left alone, all of these would die during the winter ; and that the only 
 ones destined to pass the winter are the adults which the sheep do not 
 destroy but cause to take wing. 
 
 Others have the idea that by feeding the leaves the insects will be un- 
 able to find a suitable place to pass the winter ; whereas to destroy their 
 wintering place it would be more effectual to let the vineyard alone and 
 to cause the sheep to brouse off all the citrus and other evergreen trees, 
 and all the grass and weeds along the ditches, — indeed to make the 
 whole country bare and to keep it so all winter. One would starve the 
 sheep to death before he would the bugs, and in every respect the 
 method is impossible and ridiculous. Again others think that the sheep 
 would crush those in the ground. As a matter of course there are none 
 in the ground and there is no reason to think that they would be crushed 
 if they were there. The only place that is beaten hard by sheep are the 
 paths they follow and the place they sleep at night. A few may be 
 crushed on the surface, but a hopper so feeble as not to be able to get 
 out of the way of the feet of the sheep could not withstand the winter. 
 
 Destroying the leaves. Many farmers have gone to the trouble of 
 gathering and burning the leaves, or of plowing a furrow and raking 
 them in and burying them. The reasoning is about the same as those 
 in favor of sheeping. Farmers are not alone in this matter, forentomolo- 
 
gists everywhere have repeatedly advised such a cleaning up to destroy 
 what were, or what were supposed to be, hibernating places. These 
 recommendations appear in practically every book treating on remedies 
 for insects, but it is a fact that even in cold climates, where insects do 
 hibernate, there has never been a single reliable experiment on an insect 
 of any kind that substantiates this method's claim to practical utility. 
 We do not mean that no experiments have been tried, but that not only 
 have no economic results been produced, but all results have been either 
 negative or unreliable. In our climate, with hardly any true hiberna- 
 tion and an insect that does not hibernate, this method can only be 
 futile of results. 
 
 Plowing- and rolling. This can only be done in the winter, after 
 pruning, or in the spring, before the growth is far advanced. By the 
 time the pruning is through with there will be very few of the hoppers 
 in the vineyard that are vigorous enough to get away, and it is doubt- 
 ful if those that still remain include many that would be likely to pass 
 the winter successfully. The general idea of winter plowing and roll- 
 ing is based on the supposition that the insects are in the ground and 
 could be reached by such methods. In the spring, after the hoppers 
 have attacked the vines, it is the practice of some to jar the insects onto 
 the ground in the morning, when they will not attempt to return to the 
 vine, and turn them in with plow, disk, or cultivator, or harrow and 
 sometimes follow with a crusher or roller ; and there is no doubt that 
 in this way some of the insects, perhaps quite a good proportion, will 
 be destroyed. We do not think that the results attained will in any 
 way justify the expense, and the method can only be applied during the 
 night or on a cool morning. Unless the cultivation is necessary in 
 itself it could not be thought of as a remedy for the hopper. There may 
 be opportunity of employing it economically, however, but alone it can 
 never be effectual, as it can only be used early in the spring. 
 
 Winter spraying. This luxury has often been indulged in with end- 
 less variation as to detail. Often the bark has been carefully stripped 
 off the stumps before the spray was applied. Almost every kind of 
 spray has been tried and, of course, never with brilliant results. Often 
 the farmer will say that he thinks it did some good, but none think that 
 it has paid for the trouble. The fact is that it had no effect whatever 
 on the hoppers, and as far as the hopper is concerned, all the money 
 
 spent in this way is wasted. 
 
 Summer spraying. While winter spraying is the most useless thing 
 that can be done, spraying in the summer, when there is something in 
 the vines to kill, is an effectual process. All that can be said against it 
 is the difficulty and cost. Indeed this is so great that it is doubtful if 
 it is really practicable. There is a great difference between effective- 
 ness and practicability. Nothing is practical unless it pays. When it 
 is said that spraying is effectual, the statement should be modified to 
 this extent. The insect is so active that it is impossible to prevent 
 many from escaping, and they are so difficult to wet that it is necessary 
 to use a very strong and penetrating wash like the kerosene emulsion, 
 to get even fair results. In the spring it is quite easy to spray, as the 
 
— IO — 
 
 material used can be taken through the fields on a truck, but as soon 
 as the vines cover the ground it becomes another matter. Then the use 
 of knapsack sprayers seems to be the only way to apply a spray. The 
 necessity of spraying from below increases the difficulty and expense of 
 such a treatment. The only spray that does any good is one that will 
 kill. It is not possible, for instance, to make the vines distasteful to the 
 hopper and so make it starve to death. Many things have been tried 
 for this purpose, but nothing has ever been, and probably never will be, 
 found to do it with this insect or any other. 
 
 Jarring. Jarring is one of the commonest remedies tried in the spring 
 and under some conditions it is one of the best. The sketch, Fig. i, 
 
 Fig. i. 
 
 given herewith, is one that has been used in Europe for a different kind 
 of insect, and has been recommended by European authors for their 
 vine hopper, which is related to our insect, but has never been abund- 
 ant enough to really need a remedy. It consists of a tin funnel with a 
 notch to enable it to be held under a vine and a cloth bag tied to the 
 bottom to hold the hoppers. In the next sketch, Fig. 2, is shown a 
 
 Fig. 2. 
 
 modification which differs in the addition of a conical tin handle, in 
 which may be inserted a short stick if it is desired to increase its length. 
 About a foot and a half in diameter will be found a convenient size. 
 Any tinner can readily make the funnel. 
 
II 
 
 In the work in this State the favorite form has been something like a 
 large scoop. It is generally made broad with a notch in the edge, and 
 one held on each side of the vine while it is jarred, and the insects that 
 fall on the scoop are, from time to time as they accumulate, poured into 
 a vessel containing water and a little kerosene. The accompanying 
 sketch, Fig. 3, gives a style of these scoops made of a single piece of 
 
 Fig- 3- 
 
 tin. A part of one edge is so bent as to fit a handle. The corners are 
 rounded and a notch is made in the edge opposite the handle. Two 
 men proceed up a row of vines placing the scoops below the vine and 
 one of them jars the vine with a stick. 
 
 The success of jarring will depend on preventing the hoppers escap- 
 ing from the scoops and can only be used when the hoppers will fall 
 well. It likewise cannot be used after the vines attain considerable size: 
 therefore this method alone cannot be depended on, however well it may 
 work in the spring. 
 
 The hopper dozer. Great ingenuity has been displayed in the design- 
 ing of hopper dozers. By this term is meant any contrivance against 
 which the insect may be made to leap or fall and which will cause their 
 death. Generally they are coated with a sticky substance on the prin- 
 ciple of a fly paper. Many have been made on the principle of the 
 scoops for jarring, but where tried have generally been replaced by the 
 scoop without the sticking mixture. Others which work very well have 
 been shaped like a bell jar ; this kind can only be used during the hotter 
 part of still days, while the insects fly well. Both of these forms are 
 only intended for use in the spring while the vines are small, and the 
 latter only on short-pruned varieties. They both are troublesome to 
 recharge with the sticking mixture and probably have been discarded 
 in every case after the first trial. 
 
 There is another form that has been used successfully in the eastern 
 States on a small scale, and which promises to be much more satisfactory 
 for use here than any kind as yet tried in the State. It consists simply in 
 a plain palm-leaf fan. The idea is to have a can of the sticking mixture 
 large enough to dip the fan into, and arming each man with a stick with 
 which to jar the vines, and a fan to catch the insects with, have them 
 go rapidly through the vineyard, from vine to vine. In the morning 
 while they drop, it may be well to work the men in pairs thus : Give 
 
12 — 
 
 one man two fans and the other a fan and a stick. When they come to 
 a vine the three fans will be held below the vine, touching the trunk 
 and overlapping each other. The vine is then jarred and the insects 
 caught. As the day gets warmer and some of the insects fly, those 
 that drop are first caught and then the fans at once swung catching 
 those in the air. After they cease to drop the men can work independ- 
 ently, though even then it may be well to continue to work in pairs. 
 The sticking mixture may be kept at the end of the rows. This method 
 is applicable all summer, but even this can only be used for hoppers on 
 the wing after the vines are large. 
 
 The net. The use of the insect net has not been seriously thought of as 
 a means of combatting this insect on a large scale until this year, as far 
 as we are aware. Experiments seem to indicate that it will prove thor- 
 oughly practical. The form of net that we prefer is made as follows : 
 For a net a foot in diameter take a piece of wire forty inches long, bend 
 about an inch and a half of each end at right angle, and then bend the 
 whole wire into a hoop bringing the bent ends parallel. Make a tin fer- 
 rule about six inches long, increasing from one quarter to about three 
 quarters of an inch in diameter at the larger end. Solder the ends of the 
 hoop into the smaller end and the hoop is complete. The ferrule serves 
 as a handle, or when a longer handle is needed a stick may be inserted 
 into it. The bag of the net is made of a yard of cheese cloth. Fold 
 the cloth so as to bring the selvages of one side together and sew along 
 the selvage. This will make a conical bag. Now trim the cloth so that 
 the edge is everywhere a half a yard from the point of the bag. Gather 
 the edge of the bag on the hoop, making a hem, and the net is com- 
 plete. [Fig. 4.] A net, having a diameter of a foot and a half may 
 
 Fig. 4. 
 
 be found more useful, in which case a wire about sixty inches long, and 
 four feet of cheese cloth, will be needed, but otherwise it is made in the 
 same way. 
 
—13— 
 
 In using the net one first jars the vine and, as the insects fly, a few 
 strokes with the net will catch the great majority of them, if skillfully 
 done. With a net of this shape the insects will all accumulate in the 
 tip and can be quickly crushed to death with the hand or emptied into 
 water and kerosene if desired. The practicability of the method will 
 depend on the skill of the workmen, but the skill is easily acquired and 
 most every one will get the idea at once. The nets could be used early 
 in the morning in the same way suggested in the case of the fan hopper 
 dozer. The net is equally as rapid as the fan, does not require the 
 sticking mixture and is therefore preferable ; though it may require 
 more skill in handling and therefore with some men be less satisfac- 
 tory. Like the fan method the net may be used all summer. The two 
 comprise the only methods (with the possible exception of spraying) 
 which are at all practical for summer use, at least with the Californian 
 methods of culture. 
 
 TREATMENT. 
 
 We have thus far considered the remedies available for treating the 
 vine hopper ; there yet remains to be discussed the theories and program 
 of treatment. Almost every kind of remedy that has been suggested 
 for destroying insects, has been tried for the leaf hopper without suffi- 
 cient success to justify its continuance, and either we must wait for 
 some brilliant discovery and in the meantime allow the insect to be un- 
 controllable, or we must radically change our theory of treatment. In 
 all the experiments in this State the idea has been to destroy the insect 
 in the winter or spring and to depend on that for the protection of the 
 crop through the rest of the year. The desire has been to exterminate 
 the insects or approach that result as nearly as possible ; but that has 
 proven impracticable. It seems about time to stop the war of extermi- 
 nation and turn our attention to another solution of the problem which 
 gives more reason to hope for success. 
 
 The new theory of treatment that is proposed is based on the fact ob- 
 served by all that a small, or even a considerable number of hoppers 
 does not appreciably injure the crop. Of this fact every grower in the 
 State can bear witness Good crops can be produced in spite of the 
 hoppers, and it is only their excessive numbers that are injurious. The 
 problem can be reduced then to this question : Is it possible to reduce 
 the numbers in a field below the danger mark ? It must be possible to 
 do so at any time and at a small expense. The question then arises : 
 What is the danger point? This cannot be definitely answered, but 
 observations during years when there is the greatest loss and during 
 those in which the loss is trifling leads us to believe that if the number 
 could be reduced fifty per cent, in the worst years, the injury would be 
 avoided. If it is true that such a reduction would prevent the injury, 
 the question is, Can fifty per cent, of the insects be cheaply destroyed? 
 
 According to the best estimate we could make by actual trial in the 
 field, of the effect of the use of the net in the spring, it appeared that 
 
— 1 4 — 
 
 a much larger percentage than that could be destroyed — nearer ninety 
 per cent. , and this too while working at a rate of about five acres a day. 
 About half of a gang of men green hands at the business, part white 
 and part Chinese, did almost as well as one skilled with the net. At 
 the rate of wages they were getting, the cost per acre would be between 
 fifteen and twenty cents. This makes it a wonderfully cheap process. 
 If it cost twice as much and had to be done a dozen times in a year, it 
 would not begin to cost as much as the loss to a crop in a bad year. 
 It seems to have been proven by actual test that a good percentage of 
 the hoppers can be taken and killed by the use of the net and at a cost 
 per acre that is nominal. There yet remains to be seen whether the 
 vineyardist can develop a judgment that is to be depended on as to when 
 the insects are approaching the danger point, and to set the nets going. 
 According to this new theory of treatment it would appear that we 
 have the true solution of the problem and that the net or the palm-leaf 
 fan are the means giving the greatest promise. 
 
L0UI6 ROESCH CO., PRINTERS, 8. F.