FIELD BOOK OF INSECTS. 



within the caterpillar but come out and pupate just before 

 their host dies. Bunches of such cocoons are often found 

 fastened on plants; these belong to species which leave 

 their host before pupating. Other species live in plant- 

 lice, pupating within their host's dead body and cutting 

 a neat, circular hole through the abdominal wall when 

 emerging. Usually a member of the superfamily Ichneu- 

 monoidea which has no more than two apparent, dorsal, 

 abdominal segments is a Brachonid, especially if the cut- 

 ting edge of the mandibles be turned inwardly. 



The family ICHNEUMONID.*: includes, the largest and 

 most frequently noticed species. The first abdominal 

 segment is broadened or bulbous, not cylindrical. Fre- 

 quently a promising Saturnid cocoon contains one of these, 

 Ophion macrurum (Plate LXXXVIII), instead of its 

 rightful owner. The Ophion larva, which was feeding 

 inside the caterpillar, allowed its host to live until the 

 cocoon was made, then killed the maker, spun a dense, 

 brownish cocoon of its own as an additional protection, 

 and pupated. 



A more commonly used name is Thalessa. 

 Megarhyssa 



Most of the female Ichneumonoidea carr 



their ovipositors protruding from the tip of their 

 but the ovipositors in this genus are long, even when 

 compared with the large size of insects. They are parasi- 

 tic upon wood-boring larvae, such as Tremex, and are, in 

 turn, parasitized by Ibalia. Delicate as the ovipositor 

 seems to be, the female is able, with it, to pierce solid 

 wood in order to deposit an egg in the burrow of the Tremex 

 within the tree's trunk (Plate LXXXVIII). I do not 

 know how the females decide where to bore. The egg is 

 not necessarily laid near the Tremex larva but the burrow 

 must be reached and this is rarely, if ever, half an inch 

 wide. Because of the popular interest in the subject, 

 I assure you that the creature does not sting and give a 

 modification of Mr. Viereck's key to some of our species. 



1. Wings without dark patches ...................... 2. 



Wings with dark patches; more than .75 in. long ..... 4. 



2. More than .75 in. long; exserted portion of ovipositor 

 usually at least twice the length of the body ............ 3. 



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