The Curraxt Fruit Fly. 



203 



the 7 days. The last marked fly was caught 25 days after Hbera- 

 tion. 



Egg-laying Period. 



In the season of 1914. female fruit flies were captured in 

 the field and dissected to ascertain when ripe eggs appear in tb.e 

 ovaries, and thus a clue might be obtained as to the date that egg- 

 laying is likely to begin under natural conditions. No fully 

 developed eggs were found in the internal reproductive organs 

 of specimens captured during the last week in May. On June 

 6-7, 80 per cent of the females collected contained full grown 

 eggs in the ovarioles. Females which are at the beginning of the 

 egg-laying stage can usually be recognized by the expansion of 

 the abdomen. 



Since the earliest date that egg-laying is likely to begin 

 under natural conditions has an important bearing on when to 

 apply the first application of the poisoned bait spray, female 

 flies were again captured in the field in the season of 1915, and 

 dissected to determine when mature eggs appear in the ovaries. 

 Table 12, shows the data. 



TABLE 12. 



Dissections of Flies Captured in Field to Determine When Ripe 

 Eggs Appear in Ovaries. 



Date flies 



Number 



Number o: 



E flies 



Number of flies 



were 



of flies 



with ripe 



eggs 



without ripe eggs 



captured 



dissected 



in ovaries 



in 



ovaries 



May 25 



12 











12 



30 



13 











12 



31 



13 











13 



June 1 



5 











5 



2 



16 











16 



3 



11 











11 



4 



20 











20 



5 



41 



12 







29 



6 



8 



1 







7 



7 



37 



24 







13 



' 



50 



36 







14 



Ten female currant fruit flies captured in copula on June 

 17, 1914, and 12 females on June 11, 1915, were dissected and 

 fully developed eggs were found in the egg tubes of all of them. 



