BUREAU OF ENTOMOLOGY. 229 



points in the seasonal history and habits, natural enemies, etc., which 

 would contribute to the discovery of successful methods of prevent- 

 ing the establishment and spread of these insects in this country. 



INVESTIGATIONS OF INSECTS INJURIOUS TO VEGETABLE AND 



TRUCK CROPS. 



The work of investigating insect enemies of vegetable and truck 

 crops has been in charge, as formerly, of Dr. F. H. Chittenden. 



Insect enemies of potato and related plants. — An investigation 

 of the potato-tuber moth, begun a few years ago, is practically com- 

 pleted, and a monographic account of this insect from the particular 

 standpoint of its occurrence in California, with methods of control, 

 has been prepared. The natural parasitic enemies of the tuber moth 

 aid materially in holding this serious pest in check. Work on the 

 Colorado potato beetle has been continued, with particular reference 

 to its origin and distribution, and its increasing range westward is 

 being noted. Some additional experiments have been made with con- 

 trol measures. Investigations on the potato flea-beetle, which is a 

 very troublesome pest in some regions, are being continued. Minor 

 insect enemies of potato have been the subject of considerable study, 

 and those of the tomato, eggplant, and other crops related to the 

 potato have been under constant observation. The potato thrips has 

 been studied in southern Texas as injurious to both Irish and sweet 

 potatoes, where it may be the cause of the spreading of potato 

 diseases. Among the most important of these pests are the common 

 stalk-borer, tomato fruit worm, potato stalk weevil, tomato " suck- 

 fly," and other plant bugs, aphids, etc. 



Sugar-beet insects. — The beet leafhopper has been under con- 

 tinuous observation. It is the cause of the " curly-top " disease of 

 sugar beets, and much has been learned in regard to it during the 

 year. A number of natural enemies, chiefly parasites, have been 

 reared. Particular attention has been given to the relation of wild 

 vegetation, especially weeds such as mallow and chickweed, to sugar- 

 beet infection, and a publication on this topic has been prepared. 

 Work on the sugar-beet wireworms, especially experiments on poison 

 trapping, has been continued. In Colorado continuous study has 

 been given to the sugar-beet webworm, and a report is in 'prepara- 

 tion. The insect is readily controlled by arsenicals. The western 

 cabbage flea-beetle attracts more attention as an enemy to sugar beets 

 than on its more natural food plants, cabbage and other crucifers, 

 and excellent progress has been made in its study. Arsenate of lead 

 has thus far proved the best means of controlling the pest, acting as 

 a repellent. Where the beetles occur in small areas, dusting with 

 tobacco has given fairly good results. The false chinch bug was the 

 cause of a serious outbreak on sugar beets in Kansas and Colorado. 

 Its abundance has enabled the bureau's agents in those States to 

 experiment with control measures, and the practical results of these 

 experiments are available as Farmers' Bulletin 762. Cutworms in 

 their relation to sugar beets have been studied further, and a publi- 

 cation has been issued on the variegated cutworm. The beet leaf- 

 miner has been studied in New York and California. The sugar-beet 



