EGG PARASITES OF THE GIPSY MOTH. 



181 



Fig. 21.— Schedius Jcuvanx: Egg-stalk and 

 anal shield of larva as found in host 

 eggs of gipsy moth from which the adult 

 Schedius has emerged, or in which the 

 Schedius larva has been attacked hy a 

 secondary parasite. Greatly enlarged. 

 (Original.) 



Schedius is to all purposes, if not to all intents, a secondary para- 

 site upon occasion. In the spring of 1909 a generation was carried 

 through to maturity within the larvae 

 of Anastatus, and at that time there 

 was no difficulty experienced in induc- 

 ing the Schedius females to oviposit in 

 such. In the course of later experi- 

 ments which were designed to deter- 

 mine whether there was any preference 

 shown between the eggs containing 

 healthy caterpillars and those with the 

 larva? of Anastatus, only the healthy 

 eggs were selected for oviposition by 

 the parent females. What was more, 

 although several later attempts were 

 made to force Schedius to oviposit in 

 eggs containing Anastatus larvae, none 

 but the first was successful. 



Oftentimes two or more eggs are 

 deposited in one host. Numerous in- 

 stances have been found in which second-stage larvae were feeding 

 peaceably side by side as the result of such superparasitism, and 

 still more have been observed in which the former presence of more 



than one individual was positively indicated 

 by the presence of more than one egg-stalk 

 and anal shield, but never, out of many 

 thousands of examples under observation, 

 has more than one adult parasite issued 

 from one egg. What happens to the su- 

 pernumerary individuals is not indicated 

 further than that they disappear, and that 

 their substance goes to nourish the sole survivor. Whether there 

 is an actual struggle for supremacy in which victory comes to 

 the strongest, or whether the struggle 

 takes the form of a contest to deter- 

 mine which shall quickest consume 

 the available food supply, the loser 

 calmly surrendering his body to the 

 winner by way of forfeit, has never fig.23.- 

 been revealed. dibles - 



The story of a triple tragedy is told in Plate XI, figure 3, which is 

 drawn from a slide prepared by Mr. Smith. It represents a single 

 gipsy-moth egg, which had been attacked by Anastatus before the 

 embryonic caterpillar had developed sufficiently to leave perceptible 



^ 



Fig. 22.— Schedius kuvanx: 

 Larval mandibles. Greatly 

 enlarged. (Original.) 



■Tyndarichus navse: Larval man- 

 Greatly enlarged. (Original.) 



