BUBEAU OF ENTOMOLOGY. 303 



trol measures developed by the Bureau have been generally adopted 

 by vineyardists. and it has been shown that thorough and timely 

 spraying will reduce injury to an extent that high-grade fruit can 

 be produced even in localities where berry-moth infestation is heavy. 

 Tests of the single-spray method continue to show very satisfactory 

 results and growers have^thus been able to cut down spraying costs 

 materially. However, in localities where there are unsprayecl or 

 improperly sprayed vineyards and favorable hibernating places for 

 the berry moth, two sprayings are necessary for proper control. 

 In vineyards where the berry moth, grape leafhopper, and grape 

 rootworm coexist, and where berry-moth damage is comparatively 

 light, it has been demonstrated that by advancing slightly the date 

 of application for the second brood of the berry moth, a schedule of 

 applications can be adopted which will treat all three pests by the 

 same spray application. Major attention at present is being given 

 to a careful study of several species of grape leafhoppers which 

 are just now on the increase in the territory under discussion. Tests 

 of magnesium and calcium arsenate have shown that these substances 

 are not as satisfactory as lead arsenate for appliction on grapes on 

 account of danger of injury to foliage and fruit. While calcium ' 

 arsenate has given satisfaction on Concord grapes, it produced 

 injury on certain other varieties. Tests of casein in various spray 

 mixtures were begun in 1919. Our experience indicates that while 

 the spray has good adhesive qualities, it does not spread over the sur- 

 face of the berry as readily as when resin-fishoil soap is used. A 

 small amount of soap added to the casein-Bordeaux-lead spray seems 

 to increase the spreading qualities of the spray, however. 



Studies of the grape mealybug under way in California have 

 been interrupted on account of the large mortality of the insect due 

 to season and parasitism. The experimental work therefore did not 

 show very decided results. Dormant spraying with a petroleum oil 

 emulsion gives excellent results in destroying the insects and is the 

 present recommendation for this pest. Experiments with para- 

 dichlorobenzene in the control of the grape Phylloxera are promising. 



Insecticide investigations. — Investigations of miscellaneous in- 

 secticides have been continued. Attention has been given to a study 

 of the insecticidal constituents of plants, and in cooperation with 

 the Bureau of Plant Industry a paper has been prepared on plant 

 insecticides. In this investigation 232 preparations from 59 species 

 of plants were tested against a total of 28 species of insects. In all, 

 260 species of plants have been considered, only about 5 per cent of 

 which, however, can be regarded as containing efficient insecticides. 



In the work with contact insecticides in cooperation with the 

 Bureau of Chemistry progress has been made, and manuscript giving 

 results obtained to date has been prepared. Further studies are 

 under way of insecticides from petroleum^ many oil fractions and 

 by-products of which have been and are being tested in regard to 

 their availability as contact insecticides. In cooperation with the 

 Chemical Warfare Service of the War Department and with repre- 

 sentatives of the Federal Horticultural Board, experiments are in 

 progress with numerous toxic gases to determine their availability 

 for use against insects. 



