BUREAU OF ENTOMOLOGY. 645 



the cabbage looper on cauliflower. It was found that it was necessary 

 to use some sticlcy substance in order to make the spray adhere to the 

 waxy leaves of the cauliflower. 



WORK ON INSECTS AFFECTING CITRUS FRUITS. 



The investigation of the insect enemies of citrus and other sub- 

 tropical fruits has been carried on during the past year as heretofore 

 under the direct supervision of the Assistant Entomologist, Mr. C. L. 

 Marlatt. The leading projects have been the investigation of the 

 orange thrips in California and the white fly in P'lorida, with the 

 introduction from India of predaceous and parasitic enemies of the 

 last-named insect. This attempt at introducing the natural enemies 

 of the white fly has been referred to in a previous section of this 

 report. 



WORK ON THE WHITE FLY IN FLORIDA. 



As indicated in the last report, the investigation of the white fly in 

 Florida had made substantial progress and is nearing completion. 

 The finished work included reports on life history, control by hydro- 

 cyanic-acid gas and by natural agencies, such as fungous diseases, 

 the destruction of unnecessary food jilants, and an attempt in many 

 ways to create conditions favoring immunity from attack by the fly. 

 There remained uncompleted the important means of control by 

 sprays, and work during the last year has been concentrated upon 

 these measures. Inexpensive but effective oil-soap sprays have been 

 worked out and are now being used, and these promise to settle in a 

 satisfactory manner the problem of direct control. There are now in 

 preparation or in print reports covering the completed aspects of this 

 investigation, namely, (1) ccmtrol by fumigation; (2) control by 

 natural agencies, such as fungous diseases, and (3) control by spray- 

 ing. The life-history studies have already been published. There 

 is also in preparation a report giving results of tlie explorations of 

 Mr. Woglum, the expert who was sent to India, including an account 

 of the discovery of the native home and probable original range of 

 the white fly in Asia and the facts found by Mr. Woglum in relation 

 to control by parasites in India and the methods devised for collect- 

 ing and introducing the natural enemies. 



THE ORANGE THRIPS. 



The investigation of the orange thrips at Lindsay, Cal., has been 

 continued during the past year along llie lines indicated in the last 

 report, and the demonstrational results of the spraying tests have 

 been satisfactory and have resulted in their general adoption by the 

 growers. 



For the season of 1912, already begun, there is under way further 

 demonstration spraying of orchards with limo-std]iliur at the strength 

 which past work has sliown to be most advisable, namely, a stock 

 solution of ?>()" Baume diluted for application to the trees with 50 

 ))arts of water. 



In connection with the thrips work at Lindsay, a number of other 

 troublesome pests of the orange have been investigated, particularly 



