270 



Journal of Agricultural Research 



Vol. HI, No. 3 



maggots are hatched which feed and burrow about, causing the rapid 

 destruction of the affected parts, and then leave the host to enter the soil, 

 where they pupate. After a short time the adult emerges from the pupa 

 and soon deposits eggs for the following generation of larvae. 



THE EGG 



From the data included in Table I it will be seen that the duration of 

 the egg stage of the melon fly is very short. During the warm summer 

 months, when the daily mean temperature is about 79° F., eggs hatch in 

 26 to 35 hours after deposition. The data indicate that hatching pro- 

 ceeds most rapidly about 27 or 28 hours after the eggs are laid. At a 

 mean temperature of 75.6°, 84 eggs hatched in from 31 to 38 hours, while 

 at a mean of 75°, 96 eggs hatched in about 47 hours after deposition. At 

 73.6°, 88 eggs hatched about 52 to 54 hours after being laid. 



Table I. — Duration of the egg stage of the melon fly 



THE LARVA 



The larva of the melon fly passes through three instars before being full 

 grown. The data in Table II show that at a mean temperature of about 

 79° F. larvae can complete their development in from four days and four 

 hours to seven days. The larvae recorded as feeding upon papaya {Carica 

 papaya) were transferred several times a day from one small piece of pulp 

 to a fresh piece ; hence, they probably pupated a few hours sooner than they 

 would have pupated had they undergone their entire development in a 

 single fruit. Larvae developing in thick-skinned fruits, such as water- 

 melons and pumpkins, often remain in the fruit after becoming full 

 grown several days longer before emerging to pupate than they would 

 have done had they been less confined. During the cooler seasons of the 

 year the length of the larval life will probably be found to be much longer. 



