October, '13] severin: mediterranean fruit fly 401 



with so many maggots present, som_e would not obtain a sufficient 

 food supply from the small amount of pulp surrounding the seed. 

 The largest number of adult fruit flies bred from a single tropical alm- 

 ond was 28 males and 32 females, a total of 60 flies; some of these 

 specimens were much smaller than others, but we did not determine 

 whether these were able to deposit eggs. 



In another experiment 12 infested tropical almonds were placed 

 in separate breeding jars and exposed to hot sunshine. At the end of a 

 week the pulp of these fruits becam.e hard and leathery. From two 

 of these fruits 19 larvae bored out, 7 of which died in the bottom of 

 the jars and 12 pupated, but the pupse failed to give rise to imagoes. 

 A field observation along this same line may be worth recording. An 

 orange that had been exposed to hot sunshine was found on the ground 

 and upon opening this fruit three dead Mediterranean fruit fly larv£e 

 were found. These maggots were black or brown in color and sug- 

 gested that death had been due to a bacterial or fungus disease. Mally 

 (3, p. 10) also observed many dead larvse in the fallen fruits of Citrus 

 buxifolius and concluded that after several days of very hot weather 

 the fruit ''became sufficiently hot to destroy the contained maggots." 



Pup^. — After the larvae leave the fruit they bore into the ground 

 to pupate. Rarely under normal conditions do the maggots pupate 

 within the fruit, but a few pupae have been found in the pulp of the 

 tropical almond and orange. The pupal period requires from 15 to 

 17 days, before the adults em.erge. 



Adult. — Dreyer of South Africa (1) writes: "It is well known that 

 when the flies appear on the wing their eggs are undeveloped and re- 

 quire, in order to be brought to maturity and made ready for laying, 

 a period of about 10 to 12 days during which the flies subsist on sac- 

 charine substances." An attempt was made to determine the length 

 of this period under Hawaiian conditions. A large number of fruit 

 flies were kept in captivity in breeding jars and fed on dilute molasses, 

 the juice of orange, prickly pear and on water. After having been 

 kept in captivity for 8 days, three females were dissected but no fully 

 developed eggs were found in the ovaries. Daily dissections of three 

 females were continued from now on and ripe eggs were found in one 

 fly at the end of 11 days but other females did not show mature eggs 

 in the ovaries at the end of 14 days. In all probability the effect of 

 confining the fruit flies in breeding jars plays an important part in the 

 rate of development of the reproductive organs. 



The duration of the different stages of the life history of the Mediter- 

 ranean fruit fly may be summarized as follows : 



