18 BULLETIN 491, U. S. DEPARTMENT OF AGRICULTURE. 



These fruits, which were of all sizes up to H inches in diameter, 

 averaged between three and four punctures per fruit, with a maxi- 

 mum of 15 punctures on the more exposed fruits. From 7 feet of 

 stone wall 442 fruits were gathered, and of these 193 were so badly 

 affected that they had dried up without developing seeds, and only 

 11 were not affected. From 250 fruits placed over sand 1,586 larva?, 

 or an average of 6.5 larva? per fruit, were reared. 



LIFE HISTORY AND HABITS. 



METHOD OF STUDY. 



As adults die in greatest numbers within 4S to 72 hours after 

 emergence if food is not given them, those required for future obser- 

 vation must be transferred to a place where they may be fed and 

 cared for daily. In this work the writers have found glass jars 

 9 by 12J inches covered with cheesecloth very convenient. Such 

 jars will hold from 100 to 200 flies in good condition. Fruit juices 

 of almost any sort are eagerly eaten. Water slightly sweetened with 

 pineapple (Ananas ananas) sirup was used with good results but 

 was replaced later by a mixture of water and finely divided parts of 

 papaya (Carica papaya). TVhen fed on such diluted food adults 

 thrive best on two feedings a day, one in the morning and one late in 

 the afternoon. The food may be applied in finely divided drops to 

 the sides of the jar by flirting the mixture forcibly against the 

 cheesecloth covering by means of a snapping movement of the thumb 

 and forefinger. The adults feed greedily and soon become distended. 

 In this condition many fall and rest upon the bottom of the jar; 

 hence, the less food falling on this portion of the jar the fewer will 

 be the deaths resulting from entanglement in it. Feeding by flirting 

 mixtures through the cloth covering causes the sides of the jars to 

 become soiled quickly and necessitates the changing of adults to 

 clean jars every two or three days. 



Eggs may be easily secured by suspending host fruits within the 

 jars containing sexually mature adults. Breaks made in the epider- 

 mis of the host fruit with any sharp object often insure the deposi- 

 tion of eggs in the portion of the fruit desired. By timing the expo- 

 sure of fruits with adults, eggs of definite age can be secured : and if 

 these are immediately dissected from the fruits, arranged on a green 

 leaf, and placed over a plug of wet cotton in a vial inverted in water 

 the embryonic development and hatching may be observed imder nor- 

 mal conditions of heat and moisture. In obtaining detailed data on 

 larval development single larva? upon hatching may be placed in 

 small squares of ripe papaya pulp and transferred twice daily to 

 fresh squares. Pupa? of known age can be obtained easily by placing 

 infested host fruits over sand and sifting the sand at stated frequent 



