196 



HYMENOPTEKA. 



The genus Rhyssa contains our largest species, and frequent 

 the holes of boring insects in the trunks of trees, inserting its 



remarkably long ovipositor 

 in the body of the larva- 

 deeply embedded in the 

 trunk of the tree. Harris 

 states that Wn/ssa (Pimpla) 

 (itrntii and Immtnr (Fig. 128. 

 male) of Fabricius, " may 

 frequently be seen thrusting 

 their slender borers, measur- 

 ing from three to four in- 

 ches in length, into the 

 trunks of trees inhabited 

 by the grubs of the Tiv- 

 mex, and by other wood- 

 F 'S'- '-" eating insects ; and, like 



the female Tremex, they sometimes become fastened to the 

 trees, and die without being able to draw their borers out 

 again." The abdomen of the male is very slender. 



Pimpla has the ovipositor half as long as the abdomen. P. 

 pedalis Cresson is a parasite on Clisiocampa. 



The genus Troy us leads to Ichneumon. The antenmu are 

 shorter than the body ; the abdomen is slightly petiolate, fusi- 

 form, and the second subcostal cell 

 is quadrangular. Troyns e.vesorii(s 

 Brulle is tawny red, and is a para- 

 site of Papilio Asterias. 



The genus Ichneumon (Fig. 129) 

 is one of great extent, probably 

 containing over three hundred spe- 

 cies. The abdomen is long ami 

 slender, lanceolate ovate, slightly 

 petiolate. The second subcostal cell 

 is five-sided, and the ovipositor is 

 either concealed or slightly exserted. 

 Ichneumon snttirah's Say is a very common form, and has been 

 reared in abundance from the larva of the Army-worm, Leu- 

 cania unipuncta. The body is pale rust-red, with black sutures 

 on the thorax. Another common species, also parasitic on the 



