134 PROC. ENT. SOC. WASH., VOL. 20, NO. 7, OCT., 1918 



remains attached until about two-thirds of the body is free of 

 the host. Owing to the tension [thus caused the body of the 

 larva is constricted at the point where the edge of the retreating 

 exuvium encircles it, and the head is bent downward until the 

 head shield breaks free. As this occurs the inner lining of the 

 mouth can be seen to come away as the last fine strand of the 

 exuvium. By this time all but the apical three or four body 

 segments have been withdrawn from within the host. From 

 this position the parasite immediately begins the construction 

 of its cocoon. The first process is the formation of a small mat 

 of looped silk on the skin of the host ventrad of the parasite 

 and reaching about half way around the emergence hole. With 

 this mat as a foundation the larva constructs the ventral half 

 and apical portion of the loosely woven outer layer of its cocoon. 

 This is made somewhat after the manner of a loose-meshed lace, 

 the ends of the loops being attached more or less regularly to the 

 top of the loops of the preceding row. This layer of the cocoon 

 grows rapidly up the ventral side of the larva, is narrowed off 

 toward the top, and about the apical third of the dorsal part 

 constructed while the larva still has its apical portion within 

 the body of the host. When this much is completed the larva 

 withdraws its head into the cocoon, completes its emergence 

 from the host and from its exuvium at the same time, turns 

 completely around somersault-fashion, and continues the con- 

 struction of the outer layer of the cocoon from the point where it 

 left off, finishing at the base. This done it begins the spinning 

 of the more closely woven cocoon proper. It seems to employ 

 two principal motions in this operation, sometimes moving the 

 head back and forth in a longitudinal direction and sometimes 

 describing a figure 8 transversely. 



The completed cocoon is pure white. It becomes detached 

 from the host rather easily, being attached only by one-half of 

 the loosely woven outer layer to the mat first constructed. The 

 cephalic portion of the exuvium protrudes through the emergence 

 hole in the skin of the host into the cocoon, and can sometimes 

 be extracted from the host by gently pulling on the cocoon. 



Meteorus hyphantriae Riley. 



The cocoon of this species is a beautiful piece of insect arch- 

 itecture and engineering. Swinging at the end of a crinkled 

 strand of silk of surprising strength and from a half inch to sev- 

 eral inches in length it escapes many of the dangers encountered 

 by the cocoons of less sagacious and ingenious insects. The 

 cocoon itself is clear amber in color, of nearly homogeneous shel- 

 lac-like texture, but with some strands running through it, and 



