APANTELES MELANOSCELUS GIPSY-MOTH PARASITE. 19 



These larvse are placed in trays and fed until the parasite maggots 

 issue. The maggots, upon issuing, spin their cocoons, usually attached 

 to the caterpillar or to the object on which the host was resting at 

 time of issuance. Each day the gipsy-moth larvae are fed, the trays 

 cleaned out, and all of the parasite cocoons removed. The cocoons 

 are put up in lots of 500 and kept in a refrigerator until they are 

 placed in the field. They are colonized as soon after removal from the 

 trays as possible, usually on the following day. Occasionally it has 

 been necessary to keep the cocoons in the ice chest five or six days, 

 and this has been done without any apparent injury to the parasite. 



The second method of securing material for colonization may be 

 divided into two parts, namely, the fall work which consists of 

 gathering and caring for the hibernating cocoons, and the actual 

 breeding work which is carried on in the spring. There is a great 

 mortality of wintering A. riielanoscelus^ largely due to secondary 

 parasitism, and a large number of cocoons must be gathered in order 

 to have a few adults of Apanteles in the spring to start the breeding 

 work. The cocoons are collected as soon as possible after they have 

 been found, in an endeavor to get them before the secondaries or 

 ants do. 



From 10,000 to 20,000 cocoons are collected during July from 

 places where the parasite is abundant. Some of the secondaries 

 present at this time hibernate within the cocoon, but there are many 

 which have one or more generations during the early fall. 



For a number of years these cocoons were isolated in gelatin 

 capsules as soon as they arrived at the laboratory. This prevented the 

 issuing secondaries from doing any further damage, but it was 

 found that the spring issuance of A. melanoscelus from apparently 

 good cocoons was exceedir^gly small. This was due partly to sec- 

 ondaries which hibernate within the cocoons, partly to injury while 

 handling, and considerably to the drying of the maggots of A. 

 rrhelanoscelus in the cocoons. The last two years the cocoons have not 

 been isolated, with the result that a better spring issuance has been 

 obtained. Instead of isolating the cocoons they were separated into 

 lots of 100 each and placed in glass tubes 1 by 4 inches, which were 

 plugged with cotton batting. These tubes were then placed on a 

 background of white in a warm bright place where they could be 

 watched and the secondaries were removed as fast as they issued. 

 Most of the secondaries issuing in the summer leave the cocoons with- 

 in two weeks after collection, although a few continue to issue for 

 two weeks longer. After the secondaries have stopped issuing the 

 cocoons are picked over and the empty ones and those showing ex- 

 ternal injury are discarded. Many of the cocoons which contain 

 hibernating secondaries at this time can be distinguished by a slight 

 discolored spot on the cocoon ; such cocoons also are destroyed. The 



