Nov. 25, 1918 Biology of Fruit-Fly Parasites in Hawaii 445 



Superparasitism in the field is common and indiscriminate, no pref- 

 erence for parasitized or unparasitized larvae being evident. 



The ovipositor blades of this species, though hardly one-third as long 

 as those of Diachasma tryoni, are otherwise almost identical in struc- 

 ture, position, and number. 



Of 83,304 fruit-fly larvae secured in Hawaii during 1916, 17.2 percent 

 were parasitized by Opius humilis and during 191 7, as determined from 

 collections of 72 , 1 39 larvae, parasitism 

 by this species was 12.7 per cent. 



Individuals held in glass sterilizing 

 tubes and kept in partial darkness 



lived somewhat longer than did adults ^G- ^('.-Diachasma/uUawayi: Freshly deposited 



of D. tryoni, when fed and held un- 

 der the same conditions. Of 541 individuals confined with diluted honey 

 and water as food, 18 females lived 100 days or more, two of these living 

 until 125 days old. 



DIACHASMA FULLAWAYI 



Diachasma fullawayi was brought to Honolulu by D. T. Fullaway in 

 October, 191 4. The material was secured in West Africa by D. T. 

 Fullaway and J. C. Bridwell. It was originally found in West Africa 

 by Silvestri in 191 2. 



DESCRIPlriON AND LIFE HISTORY 

 EGG 



When first deposited, the egg (fig. 26) is about 0.33 mm. long and 

 0.066 mm. wide. At maturity (fig. 27) it is about 0.66 mm. long and 

 0.22 mm. wide. Other than being slightly broader than is the egg of 

 D. tryoni, it is almost identical with the latter in development, shape, 



color, size, duration of stage, 

 and manner of hatching. 



The newly hatched larva 

 has been found to differ from 



Fig. 27. — Diachasmafullawayi.-MatUTeege. Length 0.66 mm. ,, , r r^ , 



that of D. tryoni m one no- 

 ticeable respect. The cephalic edge of the chitinized ventral portion of 

 the head bears three pointed teeth instead of two, as in D. tryoni. The 

 middle tooth is less than one-half as long as the other two (fig. 28). 

 The color of the chitin in the head is a shade darker than in D. tryoni. 

 Otherwise the two larvae are p'ractically identical in appearance, 

 movements, internal structure, feeding habits, and duration of the 

 instar. 



