No. 22.] HYMENOPTERA OF CONNECTICUT. 541 



An important parasite of the Hessian fly (Mayetiola 

 destructor) . 



P. aphidis Ashmead. 



Shining black. Head posteriorly almost smooth, face polished. 

 Antennae and tegulae black. Legs brown-black, the tarsi paler. 

 Abdomen nearly twice as wide as the thorax. Length 1.6 mm. 



Isocybus Foerster. 



I. pallipes Say. 



Black, very finely and closely punctulate. Legs honey-yellow 

 with black coxae. Pleural piece beneath the anterior wing not 

 striated. Tegulae rufo-piceous. Abdomen as long as the head 

 and the thorax, widest toward the apex. Length 3.5 mm. 



Milldale, 21 May, 1906 (B. H. W.). 



I. canadensis Provancher. 



Black, finely rugosely punctulate. Differs from the preceding 

 in having the pleural piece below the anterior wing striated. First 

 flagellar joint twice as wide as long. Length 3-3.2 mm. 



scelionim:. 



The members of this very extensive family are exclusively 

 egg-parasites, attacking practically all orders of insects, and also 

 spiders. 



They may be recognized by the generally carinated abdomen, 

 and the antennae inserted near the base of the clypeus. The wings 

 nearly always have a distinct venation. The antennae of the 

 females always have ten, eleven or twelve joints, except where 

 the joints of the club are fused together. 



Key to Genera. 



1. Abdomen oval, acute on sides, but without distinct lateral 



carinse 4 



Abdomen distinctly carinated on sides 2 



2. Abdomen long, fusiform or linear, segments nearly equal, 



postmarginal vein almost always present 19 



Abdomen oval or elongate-oval, third segment much longer 

 than any of the others 3 



3. Marginal vein very short, not longer than stigmal vein; fe- 



males usually apterous, with 7-jointed antennae having an 



unjointed club 9 



Marginal vein very long, usually five or six times the length 



v 



