HYMENOPTERA 



905 



The family Argidse consists chiefly of tropical insects, but a few 

 representatives of the family are found in this country. Among these 

 are two species of Stericttphora, the larvae of which occasionally infest 

 sweet potatoes to an injurious extent. 



Family ORYSSIDAE 

 The Oryssids 



In former editions of this book the oryssids were given the rank 

 of a suborder, Idiogastra. The adults resemble those of the Chalas- 

 togastra in the shape of the abdomen but the form and habits of the 

 larvcC are those characteristic of the Clistogastra. However, there 

 does not seem to be sufficient justification for giving the family the 

 rank of a suborder and it has therefore been referred back to 

 the suborder Chalastogastra in which it was originally placed. In 

 sequence of relationships the family should probably precede the 

 Cimbicidas and Tenthredinidas and stand in closer relation to the 

 Cephidas. The Oryssidse is a small family of rare insects, only 

 a single species of larva being 

 known in this country. 



In the shape of the body (Fig. 

 1 142, A) the members of this 

 family strongly resemble the Siri- 

 cidas. They are easily distin- 

 guished from all of the other 

 Chalastogastra by the anomalous 

 position of the antennae, which are 

 inserted far below the eyes, im- 

 mediately above the mandibles, 

 under a transverse ridge (Fig. 

 1 142, B); by the more reduced 

 venation of the wings; and by 

 the remarkable form of the ovi- 

 positor. 



In the fore wings (Fig. 1143) 

 the transverse part of vein M2 is 

 wanting; and in the hind wings 

 R4 is wanting; therefore, there 

 are no closed submarginal cells 

 in the hind wings. This combina- 

 tion of characters distinguishes 

 the Oryssidas from all of the Chal- 

 astogastra. In the Oryssidas the 

 first anal cell of the fore wings is preserved, in which respect the 

 members of this family differ from all of the Clistogastra. 



Fi 



g. 1 142. — Oryssus sayi; A, female; B, 

 head seen from in front. (From 

 Sharp.) 



