164 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



tions made at the end of the treatment are : The plants were in a good 

 growing condition, showing no ill effects from the spray application. 

 No eggs or adult forms of the midge were to be found. Six plants had 

 midge galls, the contents of which were blackened and soft as seen under 

 a binocular microscope. Many emerged adults, galls and eggs of the 

 midge were evident among check plants in another room of the green- 

 house. 



Examinations of the galls during the time of treatment showed that 

 in many cases the larvae and pupae are not killed by the spray, but that 

 the emerging adult is killed, probably by the moisture on its body com- 

 ing in contact with the dry spray material on the outside of the gall. 

 Thus to be effective in killing the midge, the spray mixture should be 

 present throughout the period of emergence. Evidence was obtained 

 which showed that at least a large per cent of the eggs are destroyed by 

 this spray. 



Conclusions 



It is the belief of the writer that the chrysanthemum midge can be 

 successfully controlled at the time of emergence of the adult by spray- 

 ing with a solution made of one volume of nicotine sulphate containing 

 40 per cent nicotine to five hundred volumes of water, to which fish oil 

 soap has been added at the rate of one ounce to each gallon of solution. 

 Since all the adults do not emerge at the same time the treatment must 

 be repeated every four or five days, as long as any living forms of the 

 midge remain in the galls. The plants must be completely covered with 

 the spray solution. 



Mr. J. G. Sanders: This insect is comparatively new to green- 

 house men, in fact it has occurred at widely separated points in the 

 country. Those of you who have not seen its work will hardly appre- 

 ciate the tremendous damage done to growing chrysanthemum plants 

 due to the stunting of the buds. 



Mr. E. R. Sasscer: For the past year or more we have been 

 conducting life-history and remedial work in Washington with this 

 insect. We found by using nicotine sulphate, and continuing to spray 

 every second or third day for a period of about 35 to 40 days, the midge 

 could be controlled. We have also tried burning nicotine papers, 

 but have found that if you burn often enough to be effective against 

 the midge, it will injure the plants. We have practically eliminated 

 this insect in a commercial house by spraying with nicotine sulphate. 



Mr. E. p. Felt: I would like to ask Mr. Sasscer if he has been 

 able to try it against the box leaf midge. 



Mr. E. R. Sasscer: No, I have not. 



