194 HYMENOPTERA. 



Emerton informs me that he has reared a Pezomachus from 

 the egg-sac of Attus, whose eggs it undoubtedly devours. They 

 are not even free from attacks of members of their own family, 

 as some smaller species are well known to prey on the larger. 

 Being cut off from communication with the external world, 

 the Ichneumon larva breathes by means of the two principal 



tracheae, which 

 terminate in the 

 end of the body, 

 and are placed, 

 according to Ger- 

 staecker, in com- 

 munication with a 

 stigma of its host. 

 From the com- 

 plete assimilation 

 of the liquid food, 

 Fig. 123. the intestine ends 



in a cul de sac, as we have seen it in the larvae of Humble-bees 

 and of Sty lops, and as probably occurs in most other larvae 

 of similar habits, such as young gall-flies, weevils, etc., which 

 live in cells and do not eat solid food. 



The first subfamily, the Evaniidce, are insects of singular and 

 very diverse form, in which the antennae are either straight or 

 elbowed, and thirteen to fourteen- 

 jointed ; the fore-wings have one to 

 three subcostal (cubital) cells, and the 

 hind wings are almost without veins. 

 In Evania and Fcenus the abdomen 

 has a very slender pedicel, originating 

 next the base of the metanotum. The 

 former genus has a remarkably short 

 triangular compressed abdomen in the 

 female, but ovate in the male. The ri - 



species are parasitic on Blatta and allies. Evania Icevigata 

 Olivier (Fig. 123, $ and pupa) is a black species, and is para- 

 sitic on the cockroach, Periplaneta, from the eggs of which we 

 have taken the pupa and adult. The eggs of the cockroach are 

 just large enough to accommodate a single Evania. This species 



