ANNUAL REPORT, 1940 69 



The average number of eggs per female midge fiy as determined by 

 dissection of 12 gravid adults of the second generation was 155.5±6.66, 

 varying from 102 to 216. 



Infested apple buds during the oviposition period of the first generation 

 flies averaged 318.1 ±13.47 eggs per bud, varying from 198 to 404. 



Applications of naphthalene flakes broadcasted under the trees reduced 

 the number, of flies of the overwintering generation emerging in cages 

 by 83.4 percent where 1 pound of naphthalene per 100 square feet was 

 applied, and by 80.9 percent where 2 pounds was used. The emergence 

 of the first generation flies under similar conditions was reduced 75.42 

 percent by 1 pound of naphthalene and 93.31 percent b}^ 2 pounds. The 

 emergence from the untreated ground was 3.56 overwintering generation 

 flies per square foot and 22.87 first generation flies per square foot. 

 Emergence of flies from dufT (dried leaves, hay, etc.) collected in the 

 experimental orchard and caged in the insectary was none from duiT 

 treated with 2 pounds naphthalene per 100 square feet compared to 28.5 

 flies of overwintering generation per pound of untreated dufY, and 3.69 

 flies of the first generation per pound of naphthalene-treated duff compared 

 to 78.46 flies per pound of untreated dufT. 



Preliminary laboratory experiments with dormant sprays on apple bark 

 containing an unknown number of overwintered midge cocoons showed 

 no survival where dinitro sprays were applied, and a small survival where 

 oil emulsion was applied or no treatment was given. These results were 

 inconclusive but offer some encouragement for control by dormant sprays 

 applied to the bark. 



Control of Plum Curculio in Apples. (W. D. Whitcomb, Waltham.) 

 The critical period of curculio activity in 1940 began on June 1, five days 

 after the normal petal fall stage, and continued to June 7. During this 

 period, sprays consisting of lead arsenate 4 pounds, wettable sulfur 4 

 pounds, and fish oil 1 pint, were applied to certain trees when the apples 

 of each variety were approximately 4/16, 5/16 and 6/16 of an inch in 

 diameter, as determined by measurements with calipers. The examina- 

 tion of 128,888 apples resulted as follows: 



