BEES, WASPS, ANTS, ETC. 



511 



Probably tlie most common of our large icliiieuuioii-flies are those of the genus 

 Ophion. The species of this genus are honey yellow in color. At night tliey are fre- 

 quently attracted by light. Ophion inacrnrum infests the American silkworm, Telea 

 2)oIi/p>hemus. The female Ophion lays a single egg in the body of the caterjiillar. 

 The caterpillar lives until after it has become full grown and spun its cocoon. It then 



Fig. 644. — a, Exoilerus marginatorius ; b, Bassus albosif/naius. 



perishes before changing to a pupa. The ichneumon larva leaves the body of its host 



and spins a dense cocoon of brownish silk withhi its cocoon. Tlie shrivelled remains 



of the caterpillar occupies a small space between the two cocoons. 



This same silkworm is infested by another ichneumon-fly, Crt/ptus extrematis. 



This is a much smaller species, and the female of it, in 



ovipositing, lays many eggs within a single caterpillar. 



The subsequent history of the sjjecies is similar to that 



of Ophion. Each Cryptus larva spins a cocoon within 



the cocoon of the silkworm. This results in the latter 



cocoon being packed full of the smaller cocoon. From 



a single Polyphemus cocoon I have bred thirty-five adult 



specimens of Grijptus. 



Two of the smaller European forms are represented 

 in Fig. 644 : Exenterus marginato- 

 rius ovipositing in a caterpillar, and 

 IJassus albosignatits approaching a 

 SyrpJiiis larva. Hanchiis falcator 

 is another common Eurojiean foi'in. 



The family Evaniid.e is a small 

 group comprising insects of very peculiar structure. 



Fig. 645. - 



Cryntus extrematis. 



They are, 



however, sometimes classed as a sub-family of the Ichncumonida'. 



They may be distinguished liy the following characters: the aii- 



tenuEe are filiform or setaceous with not more than sixteen seg- 



__ ments, usually with but thirteen or fourteen. The .abdomen is 



kjg. 646. -Bnnc/ms /ai- jointed to the dorsum of the met.athorax by a peduncle whicli 



cotoi-and pupa. sometimes arises close to the scutellum. The ovipositor is straight 



and often prominent. The fore wdngs are furnished with a distinct radial cell and 



from one to three cubital cells. The hind wings are almost without veins. The 



