298 



FIRST LESSONS IN ZOOLOGY 



fully developed ichneumon flies which gnawed their way 

 out through the horny case of the dead chrysalid. 



Sometimes yellow-jackets are infested by a strange 

 parasitic beetle called Stylops. The adult male Stylops 



'-*^:#.^, 



Fig. 235. — C;iterpillar killed by parasitic iLliueuniDn flics MLicli Iiave left 

 tlie boih' tlinjugli small lioles in the skin. (Natural size; fnim 

 specimen. ) 



beetles have four wings, but the females are wingless. 

 The young Stylops, a grub or larva, attaches itself to a 

 wasp or bee and burrows into its abdomen. Here it 

 pupates and lies with its head projecting slightly from a 



I'lii. 236. Fig. 237. 



Fig 236. — 'I"1k- |.i^a'(in horn-tail (Trcnuw). (Natural size ; from specimen.) 

 >'IG. 237. — T/m/fSSii ilriiliii),' into the burrow of Triiiu-x. (Natural size; 

 after Comstock.) 



slit between two of the body-rings of the wasp. Finally 



the adult Stylops issues and deserts the body of its host. 



One of the most interesting ichneumon flies is Tha- 



lessa, which has a remarkabh' long, slender, flexible 



