INTRODUCTION. 



Sub-Order ENTOMOPHAGA or ICHNEUMONOIDEA. 



The whole of this very extensive group is believed to be 



parasitic upon other insects, spiders, centipedes, etc., excepting 



only a part of the CTNIPID.I;. It consists of six sufficiently 

 distinct families, which are thus recognised : 



(1) EVANIIDJE alone have the abdomen rising from the dorsuin of the 



metathorax. 



(2) CYNIPIDJJ alone have the terebra partly coiled and emitted from 



near the base of the abdomen. 



(3) PROCTOTUYPIDJE alone have the terehra tubular and emitted from the 



apex of the abdomen. 



(4) CHALCIDID^ alone are strongly punctate and brilliantly metallic in 



coloration. 



) ( lack the second recurrent 



(5) BRACONIDJE / ai one have complete J nervure. 



T neuration 1 have the second recurrent 



(6) ICHNKUMOXIDJB] ( nervure. 



These last two families are undoubtedly the most highly 

 specialised in the sub-order, both as regards their structure and 

 probably also their instincts, though but little is known of the 

 habits of the smaller of even the Palsearctic ICHNEUMONID.E. To 

 the first four families the last bears no very close resemblance, 

 and from them it will at once be distinguished with a little 

 experience. But many genera of Ichneumons exhibit so close a 

 resemblance to the BEACONIDJI that the division in general use, 

 though very convenient, hardly appears natural ; they are easily 

 confused and the only sure method of discrimination is to bear in 

 mind that the ICHXEUMOXIDJE have a transverse uervure across 

 the front wing running down from the areolet to the anal nervure, 

 all trace of which is lacking in the BRACONIDJE. In a few genera 

 of the former, however, e. g., Ifemiteles, Orthocentrus, and Homo- 

 cidus, this second recurrent nervure, though always traceable, is 

 often pellucid, though usually stronger at the anal extremity ; and 

 in those genera whose wings are rudimentary no reliance can be 

 placed upon such nervures as may exist. In such cases as the 

 latter, and also in the wingless forms, it is necessary to fall back 

 upon the tegument of the abdomen, which is flexible beneath in 

 Ichneumonids, e. g., Pezomachus and its brachypterous allies, but 

 hard and chitinous, with the central segments connate and in- 

 flexible, in Braconids, e. g., Chasmodon, Pambolus, etc. 



Hence we find that an Ichneumonid always has the abdomen 

 rising from the apex of the metathorax ; the terebra straight, not 

 tubular, exserted from the ventral surface near the apex of the 

 abdomen ; the antenna} not geniculate ; the colour not or but 

 very rarely metallic, though often strongly shining; and the 

 second recurrent nervure always present, or, in apterous and 

 micropterous forms, the ventral segments not connate. 



