894 AN INTRODUCTION TO ENTOMOLOGY 



BB. No scale or nodes between the abdomen and thorax. 



C. Pronotum not movable, fused with the rest of the thorax; very hairy 



ant-like insects, usually red and black, p. 953 Mutillid^ 



CC. Pronotum movable, jointed to the rest of the thorax; less hairy insects. 

 D. Antenna elbowed; hind corner of pronotum not reaching the tegula, 

 separated from it by a special sclerite, the prepectus. p. 941 . Chalcidid^ 

 DD. Antenna not ellDowed ; hind corner of pronotum reaching the tegula. 

 E. Second and third abdominal sternites membranous, in dried speci- 

 mens with a longitudinal fold; ovipositor always exposed beyond the 



tip of the abdomen, p. 922 Ichneumonid^ 



EE. Second and third abdominal sternites sclerotized, without a longi- 

 tudinal fold; ovipositor usually retracted into the abdomen. 

 F. Front tarsus chelate; antenna with ten segments, p. 978 . Dryinid.^: 

 FF. Front tarsus normal. 



G. Abdomen compressed, covered mostly by a single tergite. p. 934 



Cynipid^ 



GG. Abdomen depressed or cylindrical. 



H. Head elongate with the antenna inserted close to the anterior 



end. p. 965 Bethylid^ 



HH. Head of normal shape, not elongate; antenna with twelve 

 segments, p. 953 Tiphiid^ 



Suborder CHALASTOGASTRA or SYMPHYTA* 



The Sawflies and Horn-tails 



This suborder includes the more generalized members of the 

 Hymenoptera, those in which the form of the body is less modified 

 and the venation of the wings less reduced than is the case with other 

 members of the order. 



The basal segments of the abdomen are similar in form and the 

 abdomen is broadly joined to the thorax as in the more generalized 

 orders of insects. The first abdominal segment is not closely anchy- 

 losed to the thorax, forming a propodeum, as is the case in the Clisto- 

 gastra, and its tergum is usually longitudinally divided on its middle 

 line. 



The adult forms of the Chalastogastra have never developed the 

 highly specialized habits and instincts exhibited by many members 

 of the suborder Clistogastra, especially by the wasps, ants and bees. 

 There are no parasitic forms in this suborder except in the single 

 genus Oryssus, p. 907. 



There are no wingless forms of the Chalastogastra. In the more 

 generalized members of the suborder nearly all of the wing-veins are 

 preserved, although the courses of the branches of the forked veins 

 have been greatly modified, as indicated on an earlier page, and as is 

 shown in the figures of wings given later. 



The ovipositor of the females is well developed and complicated 

 in structure. It is fitted for making incisions in the leaves or stems 

 of plants and is more or less saw-like in form. It is this fact that 



*The name Chalastogastra is the one most commonly applied to this sub- 

 order and for that reason is used in this work; but some authors use Symphyta, 

 which is really the older name. The etymology of these names is as follows: — 



Chalastogastra; chalastos (xaXaaros), loose; gastros {yaarpos), the belly. 



Symphyta: sym {abv), with; phyton {(j>vt6v), plant. 



