202 



Maine Agricultural Experiment Station. 1917. 



taken of the number of ripe eggs found in the ovaries. Table 

 11, indicates the results: 



TABLE 11. 

 Period After Emergence Before Eggs arc 'Developed. 



Date 



Date 



Days flies 



Number 



Number of 



Number of 



of 



of 



were kept 



of flies 



ripe eggs 



flies without 



emergence 



dissection 



m ]ars 



dissected 



m ovaries 



ripe eggs 

 in ovaries 



May 14 



May 30 



16 



10 



1 ' 



8 



16 



30 



14 



10 



2 



9 



20 



30 



10 



10 



2 



8 



Jime 1 



June 8 



7 



25 



2 

 6 

 1 

 1 

 3 



22 



In all probability, the effect of confining the insects in breed- 

 ing jars, as well as the food material employed, plays an impor- 

 tant part in the rapidity and number of eggs developed. 



An attempt was made to determine the duration of the pre- 

 oviposition period under field conditions. On the day that the 

 adults emerged in cages under natural conditions they were 

 removed, marked by amputating part of a leg, and liberated 

 in a currant and gooseberry garden. Two hundred females were 

 released in six different marked lots on May 31-June 5. Dur- 

 ing the season, twenty marked insects were captured from the 

 200 that had been set free. 



The shortest preoviposition period required 6 days under 

 field conditions but from the data at hand, no conclusions can 

 be drawn as to the maximum and average periods. As already 

 stated, a specimen which issued on June 3, was marked and lib- 

 erated on the same day and was taken in copula on June 8, five 

 days after emergence. On June 9, six days after the female 

 issued, she deposited 29 eggs in gooseberries. The average 

 maximum temperature was 77° F. and the average minimum 

 temperature 46° F. for the six days. On the other hand, a 

 marked trypetid which issued on June 1, was not at the egg- 

 laying stage on June 8, when it was captured, seven days after 

 emergence. In this case the average maximum temperature was 

 79° F. and the average minimum temperature was 44.5° F. for 



