HYMENOPTERA 927 



Subfamily OPHIONIN^ 



This subfamily may usually be recognized by its compressed 

 abdomen, though a few species have the abdomen indistinctly com- 

 pressed. All are internal parasites, usually solitary. The majority 

 parasitize caterpillars. 



The tribe Mesochorini is characterized in the key to subfamilies. 

 The species are mostly small. All are secondary parasites. The 

 female of Mesochdrns finds a host that is already parasitized and 

 probes with her ovipositor until the parasite larva is reached, where- 

 upon she oviposits within the body of the parasite. The braconid 

 genus Apdnteles is frequently attacked by Mesochorus. 



The tribe Campoplegini includes a great number of species. The 

 face is evenly convex, not separated from the clypeus by a groove, and 

 is covered by short, thick silvery -white hair. The head and thorax are 

 usually entirely black and the abdomen more or less reddish. Many 

 species are important enemies of injurious caterpillars. A colony of 

 Anisota larvse is sometimes found with many dead individuals stuck 

 to the leaves and twigs. They are swollen at the middle and shrivelled 

 at both ends. These have been parasitized by Hyposoter fugitivus 

 whose cocoon makes a swelling in the middle of the dead caterpillar. 

 Many Campoplegini spin exposed cocoons. These are closely woven, 

 oval in shape, and often whitish encircled with irregular dark 

 bands. 



The tribe Ophionini includes species with an unusual venation in 

 the fore wing. The large cell just above cell ist M2 (Fig. 1154) 

 extends further distad than does cell ist. M2. Most are night-flying 

 species about eighteen to twenty millimeters 

 long, yellowish brown in color, and with large 

 eyes. These belong to the genera Ophion 

 and Enicosplliis (Fig. 1 1 54) . They parasitize 

 cutworms and similar caterpillars. One very 

 large species of Enicospllus infests the cater- 

 pillars of the polyphemus moth and its rela- 

 tives. The caterpillar lives until it spins a 

 cocoon, but does not change to a pupa. The Fig. 1154.— Ophion. 



ichneumonid lar^^a, when full grown, spins a 



dense brownish cocoon within the cocoon of the caterpillar. Thyreo- 

 don atricolor is a large coal-black species with bright orange antennas. 

 It is often seen flying along the edges of woods in search of its hosts, 

 sphingid larvas. This species and other large ichneumonids will sting 

 with the ovipositor if not handled carefully. 



The tribe Therionini includes relatively large species with very 

 slender abdomens and the hind tarsi more or less swollen. They are 

 parasites of various caterpillars. 



Subfamily CRYPTIN^ 



The Cryptinse can usually be recognized by the exserted ovipositor 

 somewhat shorter than the uncompressed abdomen and by the fact 

 that the first abdominal segment is narrow at the base, decurved 



