1916] Williams — Egg-Parasites of the Apple Tree Tent-Caterpillar 149 



points of possible interest noted, a list of the parasites found, 

 together with some comment on their behavior and relative abun- 

 dance, seemed to be worthy of publication. 



The eggs used for one experiment were separated into four lots, 

 according to the dates of collection and the conditions under which 

 they were kept. Box No. 1 contained about 350 egg-masses, 

 collected between February 20 and March 22, in the immediate 

 vicinity of the Bussey Institution, and kept in a greenhouse until 

 the caterpillars and parasites emerged. Box No. 2 contained 

 about 180 egg-clusters, collected in a locality a few miles south 

 of the first (Stony Brook Reservation, near Hyde Park, Mass.) from 

 June 19 to June 29 (mostly on the earlier date). Box No. 3 con- 

 tained about 50, collected at the same place as those in Box No. 1, 

 but kept out of doors, so that the exact date on which they were 

 gathered is immaterial. Box No. 4 contained about 60, accumu- 

 lated in the laboratory from time to time, but, for one reason or 

 another, not placed in the other boxes. The results in these last 

 three boxes were almost indentical. 



In addition to these, about 30 egg-masses were collected in early 

 spring and placed in cold storage for the months of April, May, and 

 June. The box containing these was known as No. 5. Six more 

 masses were isolated in test-tubes for individual records. 



Caterpillars hatched from the eggs in the greenhouse about two 

 weeks after collection, and the first parasites emerged March 29, or 

 about five weeks after collection. Under natural conditions the first 

 caterpillars appeared April 19, and the first parasites, June 19. An 

 attempt was made to rear the early hatched caterpillars in order to 

 secure their eggs for experiment, but they contracted the wilt disease, 

 and perished to the last individual. It was, therefore, necessary to 

 rely on pupae collected in the field, and as these were heavily par- 

 asitized the number of adults reared from them was small. The 

 first female emerged and laid her eggs on June 29, probably a day 

 or two earlier than it would have done under natural conditions. 



Six species of parasites were bred from the eggs. They will 

 be taken up in the order of emergence. 



1. Ahlerus disiocampce Ashm., Family Eulophidse. 

 Six individuals, males and females, issued in Box No. 1 March 

 29. It was the most abundant parasite till April 10, when it gave 



