SURROUNDINGS OF GROWING INSECTS 225 



of the soft-cuticled, small-headed grub characteristic of its 

 group (Fig. use). 



The study of insect-larvae parasitic in other insects is com- 

 plicated by the fact that frequently the parasite itself is 

 attacked by a " secondary " parasite, and this in some cases by 

 a " tertiary ' parasite. Such " hyperparasitism ' is illus- 

 trated in some of the tachinids and ichneumonoids that live 

 on the " Gipsy " caterpillars mentioned above. An exceed- 

 ingly small chalcid (Melittobia acasta), of which the male is 



r 



B 



FIG. 113. THREE LARVAL STAGES OF PROCTOTRUPID PARASITE 



A, First stage (" cyclops ") larva (a, feeler ; m, mandible), x 160. B, Second instar (b, brain ; 

 r, ovary) ; C, Third instar (h, intestine ; s, salivary gland ; r, ovary), x 80. After Ganin, 

 Zeitsch. f. wissensch. Zool. XIX. 



blind and wingless, is a most deadly enemy of the tachinid 

 Blepharipa, in the buried puparia of which the active little 

 females, possessed of remarkable faculties for discovering their 

 victims and able to penetrate through the narrowest crevices, 

 lay their eggs. From a very large percentage of the cocoons of 

 Apanteles emerge not that insect, but various hyperparasites, 

 whose larvae have fed on the Apanteles pupae. The presence 

 of these intruders is recognized by the round holes (Fig. 112 bed) 

 which they bore in emerging through the side of the cocoon, 

 whereas the Apanteles imago comes out by the lifting of a 

 neat circular cap at one end (Fig. 112 a). 



15 



