

The Currant Fruit Fly. 219 



TABLE 20. 



Weekly Record of Gooseberry Drops in Commercial Garden. 

 1914 qt 1915 qt. 



June 14-20 



8 





June 13-19 . 



5 



June 21-27 



42 





June 20-26 



26 



June 28-July 4 



12 





June 27-July 3 



32 



July 5-11 



26 





July 4-10 



22 



July 12-18 



15 





July 11-17 



16 





103- 



=3 bu. 7 qt 





lor 



=3 bu. 5 qt. 



It is evident from the results recorded in table 20, that the 

 frequent destruction of fallen infested fruit can not be relied 

 upon as a measure of control under town conditions. The explan- 

 ation may be due partly to the fact that some of the larvae issue 

 from the berries before they fall to the ground. It is evident 

 from certain phases of the work on the life history of the pest, 

 that infested berries must be collected daily. In all probability, 

 currant fruit flies from outside sources invaded the locality in 

 which horticultural sanitation methods were adopted. 



One objection may be raised against this experiment due 

 to the fact that 274 marked female currant fruit flies were liber- 

 ated in the commercial garden, to determine the preoviposition 

 period and longevity of the adults. It must be noted, however, 

 that 220 females emerged in cages in this garden and that these 

 same specimens were marked and released. During the season, 

 139 unmarked female flies were captured in shady localities of 

 the commercial garden before mating commenced, and 972 

 unmarked females were caught after egg-laying began as indi- 

 cated in table 18. 



The effect of gathering fallen infested fruit during one 

 season showed a decrease in the number of currant fruit flies 

 which emerged in a cage during the following season. In the 

 spring of 1914, a cage was placed over a white currant bush in 

 the commercial garden and 535 trypetids issued as indicated in 

 table 8. No infested fruit was gathered in the season of 1913, 

 but the drops were picked up at least twice per week in the 

 season of 1914. In the spring of 1915, 180 adults issued in a 

 cage enclosing a white currant bush which was adjacent to the 

 one used in the previous season. 



