The Currant Fruit Fly. 201 



in ccTition on June 8, five days after emergence. The average 

 maximum temperature was 77° F. and the average minimum 

 temperature was 42° F. for the five days. Males which are 

 sexually mature can usually be recognized by the lateral expan- 

 sion of the abdomen, but later in the season this is not always 

 a reliable characteristic. 



Mating Period. 



Under natural conditions, the period of mating was deter- 

 mined in a commercial currant and gooseberry garden, consist- 

 ing of 100 bushes. On June 7, 1914, 38 specimens were collected 

 on the outside of two cages enclosing currant bushes and of 

 these, three pairs were copulating. Three hundred trypetids 

 were taken under scantlings of fences on June 9-10, and 21 pairs 

 were noted in coition. One pair was caught in copula on a limb 

 of a poplar tree 30 feet above the ground. A single pair of fruit 

 flies in coition were taken in the field as late as July 10. From 

 these observations it is evident that mating extended over a 

 period of '^iZ days. 



In 1915, mating commenced in the same currant and goose- 

 berry garden on June 7 , and ceased on July 6, thus covering a 

 period of 29 days (Table 18). In another currant and goose- 

 berry patch at a distance of about a mile from the commercial 

 garden, mating began on June 6, and the last pair in coition was 

 captured on July 15, a period of 38 days. 



Preoviposition Period. 



An attempt was made to determine the number of days 

 required before fully developed eggs appeared in the ovaries, 

 after the adults issued from the pupae. Fruit flies upon emerg- 

 ing were consequently confined in glass jars, the bottom of which 

 was covered with about an inch of sterilized sand and the top 

 enclosed with cheese cloth. The insects were fed daily on 

 diluted corn syrup and fresh bananas. Several times during 

 each day, water was applied to the cheese cloth with a small 

 sponge fastened to a stick. After the trypetids had been kept 

 in captivity for a period varying from 7-16 days, the flies were 

 dis'sected, the ovarioles were mounted in to to, and a record was 



