Feb. 15, 1915 Mediterranean Fruit Fly 373 



probably the most satisfactory fruit for egg deposition during a voyage, 

 as they may be had at almost all points and they keep for a considerable 

 length of time. While the female shows decided preference for certain 

 fruits, she will oviposit, when forced, in almost any fruit if oviposition is 

 not prevented by physical conditions. Fruit in a hard and semiripe 

 condition is better for oviposition than fully ripe fruit, as the latter is 

 likely to be more juicy, and very juicy fruits often cause a high mortality 

 among eggs and young lar\'ae. 



During very warm weather eggs hatch in about two days. It will be 

 seen, however, from the data in Table V that the length of the egg stage 

 is considerably increased by lower temperatures. 



At a mean temperature of 78.9° F. 134 eggs hatched between 49 and 50 

 hours after being deposited, although 12 eggs deposited at the same time 

 did not hatch until from 66 to 72 hours. At a mean temperature of 

 71° F. 695 eggs hatched within 72 hours, while 3 hatched in from 120 to 

 144 hours, or about 6 days after deposition. Eight eggs hatched between 

 4 and 4>2 days after deposition at a mean temperature of 68.7''. At 59° 

 to 62° eggs hatched in cold storage in from 5 to 7 days, and at 54° to 57° 

 in from 7 to 14 days after deposition. 



LARV^ 



The larvae pass through three instars, which may be readily distin- 

 guished. Of chief interest in connection with this paper is the length of 

 larval life. The data in Table VI show that this may be as short as 5 or 

 6 days when the mean temperatures average about 77° F. One larva at 

 this temperature required 14 days to become full grown. 



The character of the fruit often influences the length of the larval stage. 

 In citrous fruits, especially in limes and lemons, it appears to be longer. 

 Thus larvae require 14 to 26 days to reach maturity in a ripe lemon, as 

 compared with 10 to 15 days in a green peach. Citrous fruits, however, 

 are not desirable for rearing work with either flies or their egg parasites. 

 For successful rearing work, where it is desired to prolong the length of 

 larval life by slightly lowered temperatures, adults should not be permitted 

 to lay more than 50 to 150 eggs in such fruits as the apple. The feeding 

 of larvae in overinfested fruits brings about such a rapid decay that few 

 become well grown. At 56° to 57° F. larvae have become full grown and 

 emerged from slightly infested apples in a refrigerator over a period 

 ranging from 36 to 53 days after hatching. 



