180 



PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



Sometimes, and apparently usually, the end of this stalk passed 

 through the shell of the egg as well as through the body of the cater- 

 pillar, as indicated in the figures (fig. 19, PI. XI, fig. 3). When the egg 

 hatches, the larva does not entirely leave the shell, but remains with 



its anal end thrust into it, and the stalk, 

 which is hollow, becomes functional and acts 

 like a lifeline attached to a submarine diver 

 in supplying a connection with the outer air. 

 As the larva grows the stalk increases in thick- 

 ness, and the last anal segment of the larva 

 becomes covered with a thick chitinized shield, 

 which is unaffected by the action of strong 

 caustic potash. There are two larval molts, 

 and consequently three larval stages. During 

 the entire course of both the first and second 

 the young parasite remains quite firmly at- 

 tached to its anal shield and lifeline and the 

 cast skins are not entirely sloughed off, but 

 are merely pushed backward. After the third 

 ecdysis it retains this connection for awhile, 

 and grows rapidly, but about the time when 

 it reaches maturity the connection with the 

 shield is broken, thus proving that it is not part and parcel of the 

 integument. It would appear rather that this shield, including a tube 

 within the egg-stalk (which, as stated, grows in thickness after the 

 egg itself hatches), is actually part of the integument 

 of the first-stage larva, and that the second and third 

 stages merely continue to use what is in effect the skin 

 of the first larval molt. 



The host caterpillar is completely destroyed except 

 for the harder chitinous parts, head, tarsal claws, hooks 

 of the prolegs, etc., and the hair, which is left in a sort 

 of hank, more or less completely surrounding and con- 

 cealing the parasite larva. It is impossible to distin- 

 guish between the larvse of Schedius and those of its 

 secondaries from an external examination of the eggs. 



After the larva reaches its full growth and casts off 

 its anal shield, it quickly pupates (fig. 20) and very 

 shortly thereafter issues as an adult. There is no indication of a 

 desire to hibernate during any part of the preliminary stages, in 

 which respect Schedius differs from nearly every other chalcidid which 

 has been studied at the laboratory. 



Fig. 19. — Schedius kuvanx: 

 Third-stage larva still retaining 

 attachment to egg-stalk, and 

 anal shield. Greatly enlarged. 

 (Original.) 



Fig. 20.— Schedius 

 Tcuvanx: Pupa. 

 Greatly en- 

 larged. (Origi- 

 nal.) 



