892 AN INTRODUCTION TO ENTOMOLOGY 



KEY TO THE FAMILIES OF THE COMMONER CLISTOGASTRA* 



Bv Dr. H. K. Townes 

 A. Wings present. 



B. Either the antenna with more than thirteen segments or the hind wing 

 without closed cells ( = cells completely surrounded by veins) ; legs usually 

 with two trochanters (parasitic Hymenoptera). 



C. Antenna with seventeen or more segments, rarely as few as fifteen; 

 costal cell of front wing obliterated by the fusion or close approximation 

 of the costal and R + M veins; hind wing nearly always with closed cells. 

 D. Fore wing with vein M2 so that cells Mi and i st M2 are separate, p . 922 



ICHNEUMONID^ 



DD. Fore wing lacking vein M2, cells Mi and ist M2 confluent, p. 919 

 Braconid^ 



CC. Antenna with sixteen or fewer segments; costal cell of fore wing present 

 though usually very narrow, or rarely completely absent. 

 D. Abdomen attached high on the thorax (alitrunk) so that there is quite 

 a distance between its base and the bases of the hind coxse. 

 E. First abdominal segment cylindrical, set off from the rest of the 

 abdomen which is small and oval ; anallobe present, p. 949.Evaniid^ 

 EE. First abdominal segment gradually enlarged toward the apex, 

 not set off from the rest of the abdomen; anal lobe absent. 

 F. Hind tibia strongly swollen toward the tip; fore wing can be 



folded lengthwise, p. 930 Gasteruptiid^ 



FF. Hind tibia not swollen toward the tip; fore wing can not be 



folded, p. 929 AuLACiD^ 



DD. Abdomen attached low on the thorax so that its base is next to those 

 of the hind coxag. 

 E. Hind margin of hind wing with a deep notch which sets off an 

 "anal lobe." 



F. Body metallic greenish or bluish; abdomen with three or rarely 

 four exposed tergites and concave beneath, p. 951. .CHRYsmiDiE 

 FF. Body not greenish or bluish; abdomen with more than four ex- 

 posed tergites and convex beneath. 

 G. Antenna with ten segments; front tarsus of female usually 



chelate, p. 978 Drvinid^ 



GG. Antenna with twelve or thirteen segments; front tarsus of 



female simple, p. 965 Bethylid^ 



EE. Hind margin of hind wing without a notch. 



F. Hind corner of pronotum not reaching the tegula, separated from 

 it by a more or less distinct sclerite, the prepectus; middle tibia 

 with one apical spur or rarely none; fore wing with only a single 

 distinct vein which is usually forked at the tip; antenna elbowed. 



p. 941 Chalcidid^ 



FF. Hind corner of pronotum reaching the tegula, the prepectus 

 absent ; middle tibia usually with two apical spurs ; antenna usually 

 not elbowed. 



G. Abdomen more or less compressed, polished, and most of it 

 covered by a single tergite; costal vein absent; cell 2d Ri + R2 



large, p. 934 Cvnipid^ 



GG. Abdomen cylindrical or depressed; costal vein present or cell 



2d Ri + Ro small or absent. (Proctotrupoidea) 



H. First segment of hind tarsus one fourth as long as the second; 



second to fourth abdominal segments of female each as long 



as the head and thorax together; abdomen of male shorter 



and clavate; large species, p. 932 Pelecinid^ 



HH. First segment of hind tarsus longer than the second; 

 second to fourth segments of abdomen not exceedingly long; 

 mostly very small species, (other families of Proctotrupoidea) 



^_ See other key at II on page 909. 



*A complete key to the Clistogastra including the uncommon and aberrant 

 forms will be found on page 908. 



