BUREAU OF ENTOMOLOGY. 317 



and studied have proved of considerable economic importance. The 

 addition of a spreader, such as lime, gelatin, or fish-oil soap, was 

 determined to be essential in control by arsenicals, since on straw- 

 berry foliage the under surface, which must be reached in order to 

 poison the insect, is strongly pubescent and ordinary sprays applied 

 without a spreader tend to collect in drops instead of giving an even 

 coating. Spraying should be applied as soon as the eggs hatch, be- 

 cause later the larvae construct protective tents or roll the leaves. 

 Burning and cleaning the fields as soon as the crop is removed is 

 also a measure of importance. A report covering this work is avail- 

 able as a bulletin. Observations and control experiments on the 

 strawberry weevil were continued in the Chadbourn (N. C.) district. 

 The strawberry leaf-beetle {Haltica litigata) was the cause of con- 

 siderable concern in Louisiana, where nicotine dust proved effective. 

 Life-history work on this species has been begun. 



SuGAR-REET INSECTS. — Work OR the curly-top leafhopper in co- 

 operation with the Bureau of Plant Industry has continued. The 

 exact limits of overlapping generations have been the subject of 

 cage experiments, and one year's breeding work has been completed. 

 Particular attention has been given to the native flora which might 

 serve as reservoirs for curly-top virus and the relation of filaree and 

 C henopodiwni murale is also being investigated. The production 

 of resistant seed at Riverside, Calif., through the medium of inocu- 

 lated stecklings is developing some promising features. Although 

 the plants are inoculated from one to three times, a large percentage 

 of the best selections show normal growth. 



Nicotine dust as a means of insect control. — In previous para- 

 graphs mention has been made of the value of this insecticide and 

 deterrent for specific insect pests affecting vegetable and truck crops. 

 It is hoped that a dust will be developed from which all of the 

 nicotine will be available, since, as at present manufactured, a certain 

 proportion of the nicotine is unavailable, with consequent waste of 

 expensive material. 



General truck-crop insects.- — The Porto Rico mole cricket, re- 

 cently introduced into South Carolina, has been the subject of experi- 

 ment with poisoned baits with excellent success. The results of 

 several years' work on blister beetles, important enemies of vegeta- 

 bles and truck crops in the West, have been completed and pub- 

 lished. 



SOUTHERN FIELD-CROP INSECT INVESTIGATIONS. 



Investigations of insects affecting southern field crops have been 

 continued under the direction of Dr. W. D. Hunter. 



Cotton insects. — As in preceding years, the work has been cen- 

 tered around the further development of the process of controlling 

 the boll weevil by dry calcium-arsenate dust. Studies in the appli- 

 cation of this poison were continued at tlie various field substations 

 under the direction of the Delta Laboratory. Plat tests were car- 

 ried through to completion in Mississippi, Alabama, Texas, Georgia, 

 and South Carolina. Much valuable information was obtained in 

 this way as to the modifications of the poisoning system necessary 

 to successful weevil control under varying conditions and in widely 

 separated cotton-growing regions. It was found that in most cases 



