The Currant Fruit Fly. 185 



It is evident from this table that the egg period required 

 from 4—7 days ; the larval stage from 10-18 days and the egg 

 plus the larval periods from 16-23 days in the different fruits. 



Egg and Larval Periods Under Field Conditions. 



In 1915, the duration of the egg and larval periods was 

 determined in gooseberries and red curants under field conditions. 

 No trouble was experienced in causing the trypetids to oviposit 

 in confinement in the field. On June 22, at 6 A. M. 100 female 

 currant fruit flies, which had been captured in the field, were 

 liberated in a cage enclosing a gooseberry bush, and by 6 P. M., 

 all of the specimens had been removed. On June 25, 150 females 

 were set free in a cage covering a red currant bush and at the 

 end of the day the insects were removed. As the minimum lar- 

 val period under laboratory conditions required 10 days, it was 

 decided to allow the fallen fruit to remain on the soil below 

 ground cages until the tenth day after the eggs had hatched. 

 The drops were then placed in sanitary fruit jars which rested 

 on the ground in the shade but were protected from rains. All 

 fruit which dropped on or after the tenth day was placed in jars 

 immediately. In the containers the fruit soon became covered 

 with fungi and few maggots completed their development com- 

 pared with the number of infested berries. The duration of the 

 egg and larval periods is shown in table 3. 



