168 



ENTOMOLOGY. 



Family Evaniidas. — These are insect-parasites, and are characterized 

 by the abdomen being attached to the disk or near the base of the 

 metathorax, and not at the apex as is the case in the other families. 

 The abdomen is petiolate and more or less compressed. Evania 

 Icevigata Olivier is parasitic in the eggs of the cockroach (Peri- 

 planeta). Fcenus jaculator Linn, in Europe lays its eggs in the larvae 

 of Crabronidae. 



Family Trigonalidae. — Costal and sub-costal veins separate and dis- 

 tinct, the costal cell being present. Abdomen sub-sessile, short, 

 ovate. Trigcnalys. 



Family Ichneumonidae.— In this great family the costal and sub- 

 costal veins are confluent, the costal cell therefore absent, while the 



first sub-marginal and first dis- 

 coidal cells are always confluent; 

 the head is generally transversely 

 oblong, and the abdomen is 

 slender ovate, usually pedicelled, 

 and the ovipositor varies much in 

 length, being longest in Rhyssa. 



The ichneumons lay their eggs 

 on the head or other parts of the 

 bodies of caterpillars, spiders, etc. 



Fig. 212.— Rhyssa. Nat. size. Fig. 213.— Ophion macrurum. Nat. size. 



On hatching, the larva, which is a soft, fleshy, footless grub, bores 

 into the body-cavity of its host, and lying there absorbs the blood 

 flowing around it, and thus weakens the caterpillar, so that it dies, 

 or the insect does not live bej'ond the pupa state. Typical genera 

 are Ichneumon, Ophion, Cryptus, Pimpla, etc. 



Family Stephanidae. — In this very small group the head is globose, 

 the vertex tuberculate and rugose; the costal and sub-costal veins 

 separate and distinct, the costal cell being present. 8tep7>anv.s 

 cinclipes. 



