928 AN INTRODUCTION TO ENTOMOLOGY 



and broadened at the apex and with the spiracles much nearer the 

 apex than the base. The species are external parasites of pupas and 

 prepupse in cocoons. A few parasitize wood-boring beetle larvse or 

 are internal parasites of dipterous larvse. 



The tribe Hemitelini includes small species with the outer vein 

 of the areolet lacking so that the areolet is incompletely formed. 

 Hemiieles parasitizes a variety of pupas enclosed in cocoons and often 

 attacks cocoons of other ichneumonids and of braconids, thus be- 

 coming a secondary parasite. Gelis is very similar to Hemiteles in 

 appearance and habits except that the females are always wingless. 

 The males may be either with or without wings, even in the same 

 species. The wingless forms have a superficial resemblance to ants. 

 Besides attacking various small insect cocoons, Gelis often parasitizes 

 the egg cocoons of spiders. 



The tribe Phygadeuonini has the areolet complete and the pro- 

 podeum with both longitudinal and transverse carinas. It includes a 

 large number of rather small species parasitic on Lepidoptera and 

 Diptera. 



The tribe Cryptini differs from the two preceding tribes by having 

 two transverse and no longitudinal carinas on the propodeum. The 

 larger species of the subfamily belong here. Agrothereutes extremdtis 

 infests the cocoons of the cecropia moth. The odor of fresh silk 

 draws the female parasite to the newly spun cocoon of the host. 

 About thirty parasites develop in each cocoon. Agrothereutes nuncius 

 parasitizes the promethea moth, and a third species of the genus at- 

 tacks the polyphemus. 



Subfamily ICHNEUMONIN^ 



Members of this subfamily resemble the Cryptinas in general ap- 

 pearance but lack a definite stemaulus, have a short ovipositor, and 

 are more stocky in build. They are all parasitic upon lepidopterous 

 pupas. The female oviposits into either the host larv^a or the pupa, 

 but the adult emerges from the pupa in both cases. 



In the tribe Phccogenini the propodeal spiracles are round. Other 

 members of the subfamily have these spiracles long and oval. The 

 Phccoginini are small species parasitic upon Microlepidoptera. 



The tribe Ichneumonini comprises many species about thirteen 

 millimeters long and somewhat wasp-like in appearance. It may be 

 distinguished from the preceding tribe by the long oval propodeal 

 spiracles and from the following tribe by the fact that the scutellum 

 is usually fiat or convex, and not subconically elevated. In this tribe 

 the females are usually of a more stocky build than the males and 

 often so differently colored that it is difficult to decide which males 

 belong with the various females. The sexes also differ in habits, the 

 males being entirely free-living and the females of many species 

 spending much of their time searching for hosts in grass tufts and 

 under dead leaves and debris. Females may be found overwintering 

 in rotten logs, under bark, and in tufts of grass. Some species enter 

 hibernating quarters in August, long before the first signs of cold 

 weather. Each kind occurs in a particular type of shelter and is not 



