solitary larva or a collection containing only a few individuals was 

 received, since parasitization or disease might prevent determination 

 if identification was delayed for the emergence of adults. Further- 

 more, when a species was received for the first time one or more repre- 

 sentative larvae were hiflated or placed in preserving solution for 

 future reference. These larvae were invaluable as aids in identifying 

 species that appeared in abundance only at long intervals, as well as 

 solitary larvae that were seldom found. 



The type of cage used depended upon the number of larvae and 

 whether they required soil for pupation. I.arvae that did not require 

 soil were placed in wooden trays with cloth bottoms and glass tops, 

 pasteboard boxes, small tin cans, or glass jars. Those that required 

 soil were placed in glass-covered metal trays with at least a part of the 

 bottom covered with fine mesh wire, or in various types of glass jars 

 and tin cans into which had been placed layers of sifted soil or peat 

 moss. 



Each collection of larvae was supplied with its proper food and 

 cared for throughout the larval instars. From this time until all 

 possibility of adult emergence had passed, they -were examined regu- 

 larly for issuance of adult parasites. Then containers with hiber- 

 nating material were stored during the late fall and winter, in a cool 

 place where temperature fluctuations were slight. During the spring 

 (and, for a few species, throughout the summer) this material was 

 examined regularly for issuance of adults and parasites. 



Certain hymenopterous cocoons and larvaevorid puparia that nor- 

 mally pass the winter in the ground were successfully carried through 

 hibernation in glass cyUnders with bottoms of plaster of paris, and 

 with clean sawdust as a substitute for soil. Glass vials with cotton 

 plugs were satisfactory as issuance containers for many species of 

 parasitic Hymenoptera, such as species of Apanteles, Bracon, Meteorus, 

 and others. The adults of the Larvaevoridae and the larger Hy- 

 menoptera were killed and pinned while fresh and given temporary 

 labels bearing the rearing number and date of issuance. The smaller 

 Hymenoptera, after being killed, were placed in small glass vials with 

 suitable labels, and were relaxed and pinned or placed on card points 

 during the following winter. 



Parasitism and Hyperparasitism 



Host insects, with very few exceptions, were collected while in the 

 immature or larval stages. Therefore, they had not been exposed to 

 the extremes of parasitization such as might have occurred had they 

 been left in their natural habitats. Parasites that emerge from larvae 

 in the early instars were likewise often missed because the bulk of the 

 collections were made when the larvae were from haJf to nearly full 

 grown. For ttie same reason, parasites that attack their hosts during 

 the last larval instar or in the pupal stage also probably were missed. 

 Parasite cocoons and puparia formed after the arrival of their hosts at 

 the laboratory usually were not exposed to secondary parasites that 

 normally attack them in this stage under natural conditions. Such 

 species of hyperparasites as were reared from them, therefore, must 

 have attacked the primary parasite while within its host prior to the 

 time of collection. For the above reasons the parasite lists given here 

 are not to be considered complete for any of the hosts. 



