April, '19] 



GUYTON: CHRYSANTHEMUM GALL MIDGE 



163 



Control Work 



Nicotine sulphate solutions were used first of all with a hope of 

 penetration sufficient to kill the larvse within the galls. Upon examina- 

 tion a few hours after application a number of dead individuals were 

 found at the point of emergence from the gall. Cages were at once 

 prepared and tests made with the following results: 



Table L Results of Nicotlne Sulphate Spray on Emerging Chrysanthemum Midge. 



The cages were prepared by placing a heavily gall-infested plant in a 

 five-inch flower pot, and covering the surface soil with about one-half 

 inch of pure quartz sand. The plant was caged by placing a large 

 lamp chimnej^ over it. The top end of the lamp chimney was closed 

 with one thickness of cheese cloth. 



Greenhouse Tests of Nicotine Sulphate 



A bench about twentj'- feet long and three feet wide, containing about 

 250 plants of a number of varieties of chrysanthemums, all infested 

 with galls of the midge, was used as a trial. The plants on this bench 

 were the only chrysanthemums in this particular room of the green- 

 house, and they were cared for as in the usual practice of the caretakers. 

 The plants were sprayed with a one to five hundred solution of nicotine 

 sulphate and water, to which one ounce of caustic soda lish oil soap had 

 been added to each gallon of solution. The spray was applied six times 

 in all, with five-day intervals between each application. Observa- 



