46 



RESULTS FROM GIPSY MOTH PARASITE LABORATORY. 



separation of the cliitiiioiis rings or plates by a stretching of the 

 intersegmental membranes which are transparent. (See fig. 26, d,d' .) 

 The underside of the planidium also gradually fills out until the larva 

 lias attained a bulk several times greater than that of the hiber- 

 nating planidium and presents the appearance of an ovate semitrans- 

 parent sack with dark median crossbars dorsally. 



After a short resting period, ecd^^sis takes ])lace. The skin of the 

 })lanidium breaks transversely just back of the second thoracic seg- 

 ment, the posterior segment slips backward, and the old head and 

 first two thoracic segments are shed at the anterior end of the larva. 

 Just how long the ])lanidium feeds before ecdysis has not been ascer- 



FiG. 26. — a, Pupa of Varichxta aldrichi parasitized by Pcrilampus Tiyalinus; b, unparasitized pupa of 

 Varichxta aldrichi; c, planidium of Pcrilampus Tiyalinus before feeding; c', same, more enlarged; d, 

 planidium of Pcrilampus hyalinus after feeding; d', same, more enlarged. (Original.) 



tained. The period probably varies greatly in accordance with the 

 prevaihng temperature. Usually, though not always, the larva crawls 

 away a short distance before it resumes feeding. 



After settling down the second time it is likely to remain stationary 

 for the rest of the larval and tlie pupal life. The larva in the second 

 stage is of a whitish color, with the tracheal s^^stem shomng through 

 the trans])arcnt skin. The body is ovate in shape, with the head 

 bent underneatli tlie anterior ]wrtion. The growth during this stage 

 is little compared to that accomplished in the third, and after feed- 

 ing a short time the s(^cond ecdysis takes place. 



(jrowth now becomes quite rapid and the larva assumes a very 

 difl'erent appearance. (See fig. 27.) The mandibles have not increased 

 in size to any great extent, but the mouth as a whole and the head 



