MEDITERRANEAN FRUIT FLY IN HAWAII. 



49 



LIFE HISTORY AND DESCRIPTION. 



THE EGG. 



DESCRIPTION. 



The eggs (figs. 3-6) are glistening white, about 0.945 mm. long, 

 elongate elliptical, and often more convex on the dorsal side. 



DURATION OF EGG STAGE. 



Martelli gives the duration of the egg stages at Portici, Italy, as 

 2 days in August and from 4 to 5 days in October. Newman states 

 that in Western Australia eggs hatch in from 



2 to 4 days during summer and in from 14 to 

 19 days during winter. Mally, in South Africa, 

 found the egg stage to be from 2 to 4 days in 

 midsummer. Other data have been published 

 but give no additional information and, being 

 unaccompanied by temperature records, may 

 be omitted. Newman appears to be the only 

 investigator who has made an effort to secure 

 data for the winter period. 



In Honolulu, or littoral Hawaii in general, 

 the length of the egg stage is very short, and 

 agrees with the minimum periods indicated by 

 writers in other countries. In Table XII are 

 recorded data on observations on 4,066 eggs 

 secured at Honolulu, which indicate that the 

 largest number of eggs hatch in from 2 to 



3 days after deposition during the hottest 

 weather. At a mean temperature of 79° F., 208 



eggs hatched in 



from 49 to 51 



hours after 



deposition, 



while 79 



hatched in 



from 52 to 53 



hours, and 3 in from 53 to 54 hours. 



At a mean temperature of 78.9° F., 



134 eggs hatched between 49 and 54 

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

 did not hatch until from 66 to 72 hours later. At a mean of 71° F., 

 695 eggs hatched within 72 hours, while 3 hatched in from 120 to 

 144 hours, or about 6 days after deposition. At a mean of 70.5° F., 

 437 eggs hatched in from 77 to 83 hours after deposition and 227 

 after a period of 83 to 91 hours had elapsed. At a mean of 69.8° F., 

 81340°— 18— Bull. 536 4 



X8 



Fig. 6. — Cross section of peach, showing egg 

 cavity of the Mediterranean fruit fly with 

 eggs. Drawing made directly after oviposi- 

 tion. (Authors' illustration. ) 



Fig. 5. — Section of grapefruit 

 rind, showing two egg cavi- 

 ties, one in cross section. 

 Drawing made one week after 

 fruit was picked. Note coni- 

 cal elevation about the egg 

 cavities left by the withering 

 of the rind; also the thick- 

 ened walls of the egg cavity 

 and the single larval channel 

 in the rag. (Authors' illus- 

 tration.) 



