October, '16] BRIDWELL: FRUIT-FLY PARASITE 473 



for several purposes besides. These experiments and others relating 

 to the adaptability of the parasite to its host in various fruits were 

 carried on in the latter part of 1913 and the early months of 1914. 

 The writer's sudden and unforseen departure in June, 1914, for the 

 west coast of Africa interrupted these experiments and has prevented 

 an earlier report upon them. 



At the time of Professor Silvestri's arrival in Honolulu in May, 

 1913, no method of breeding generation after generation of Opiine 

 Braconids (or, indeed, other normally mating Braconids) in captivity 

 had been worked out. Accordingly the material of the Opiines, Optus 

 humilis and Diachasma tryoni, brought with him by Professor Silvestri, 

 and those emerging soon after, were divided into two lots, one of which 

 was retained in captivity for breeding and the other liberated by Mr. 

 D. T. Fullaway, as previously mentioned, in the Kona coffee fields. 

 The material of Optus perproxinnis was at the time, June 13, 1913, 

 reduced to a single female and this was retained in the insectary. 



Upon Professor Silvestri's departure the breeding work was carried 

 on according to his plans by Mr. Fullaway and the writer, the work 

 upon the Opiines falling to Mr. Fullaway. The methods employed 

 were briefly as follows : The parasites, both sexes together, were kept 

 in 6-inch test tubes and provided with food (honey and water) upon 

 leaves. The tubes were kept in cardboard trays lying down and 

 shaded and partially darkened by a covering paper. When it was 

 desired to employ them in breeding, fruit was placed on dampened 

 sand in tall, narrow jars placed on their sides with the bottoms toward 

 the light. The parasites were permitted to escape from the tubes into 

 the jars and remained there for some hours. The fruit and damp sand 

 had a tendency to ''sweat" the glass and great care was necessary to 

 avoid the destruction of the parasites through their coming in contact 

 with the wet glass. The fruit-fly puparia from fruit exposed to the 

 parasites were kept with sand in shell vials of about 1-inch diameter 

 until the parasites emerged with the flies. The net results of the use 

 of this method were as follows: 



Diachasma tryoni, 334, of which 19 from a single lot of puparia were 

 females. 



Opiiis humilis, 56, all males. 



Opius perproximus, 17, all males. 



The last emergences were on August 18 and upon the writer's taking 

 up the direction of the breeding work on October 1, only a few linger- 

 ing males of D. tryoni were in the insectary. From the areas in Kona 

 where the Opiine parasites had been liberated June 13, small lots of 

 coffee were brought into the insectary and on October 10 and 26 in- 

 dividuals of Opius humilis emerged from the puparia so secured. A 



