BULLETTN 1028, U. S. DEPARTMENT OF AGRICULTUEE 



tirely stramineous, and the three basal abdominal tergites are more 

 coarsely rugose, the roughening. on the third tergite extending well 

 toward the posterior margin medially; the narrow lateral mem- 

 branous margins on the apical fourth of the first abdominal tergite 

 are testaceous in A. solitaHus, while they are piceous black in A. 

 melcmoscelus. 



METHODS USED IN BIOLOGICAL WORK. 



As this species hibernates as a maggot within its cocoon, it is a 

 simple matter to gather material during the fall and winter for study 

 in the spring. The cocoons were kept in the laboratory yard during, 

 the winter, in cylindrical cages 3 by 8 inches, made of very fine copper 

 netting. Occasionally during the winter a few cocoons were dis- 

 sected to ascertain the condition of the maggots and to note any 

 changes which might have taken place. As spring approached, the 



cocoons were iso- 

 lated, being placed 

 in small gelatin 

 capsules, or small 

 glass vials 1^ inches 

 by ^ inch. It is nec- 

 essary to isolate each 

 of the cocoons at 

 this time of the year 

 for two reasons : 

 First, so that one 

 may know the exact 

 age of the adults 

 with which he is 

 working and keep the males and females separate; second, to pre- 

 vent any secondary parasites which may issue from the cocoons 

 during the spring from ruining the rest of the Apanteles material. 

 As soon as the Apanteles issued they were removed from their con- 

 tainers and placed in glass tubes or glass-covered trays (fig. 1) , where 

 they were fed a mixture of equal parts of water and honey. A con- 

 venient method of feeding is to dampen a small piece of clean sponge 

 with the food and place it in the tube or tray containing the Apan- 

 teles. The sponge should be washed out every day or so and damp- 

 ened again with a fresh mixture of honey and water. 



Parasite-free gipsy-moth larvae were obtained by rearing them 

 from eggs, and a supply was kept in trays protected from parasites 

 ready for use at all times. 



Two sizes of g^lass tubes were found convenient, a small one 4 

 inches by 1 inch for isolated individuals, and a larger size, 8 by 2 



Fig. 1. — Tray with glass top used in life-bistory experiments 

 with Apanteles melanoscelus. (After Culver.) 



