HYMENOPTERA 



965 



Some members of the Larrini (Tdchysphex) dig short burrows in 

 the ground at the bottom of which the prey is placed with an egg, 

 and then the burrow is closed with loose sand, there being no well- 

 formed cell ; several of these burrows are often made and stored in a 

 single day. Other members of the Larrini make deeper burrows 

 which contain from a few to many cells. 



For a monograph of this tribe see Fox ('93). 



Tribe DINETINI 



In this tribe the anal lobe of the hind wings is small, not reaching 

 to opposite the apex of cell Ms+Cui+Cu; the ocelli 

 are normal, circular and convex. 



The tribe is composed chiefly of small and little 

 known insects except the genus Lyroda. A common 

 species of this genus, Lyrdda subita, practises progressive 

 provisioning, feeding its young from day to day with 

 crickets of the genus Nemobius; its nest is made in the 

 ground. The small wasps of the genus Miscophus prey 

 on spiders. 



For a monograph of this tribe see Fox ('93). 



Subfamily TRYPOXYLONIN^ 



This subfamily includes a single tribe, the Trypoxy- 

 lonini. In these wasps the inner margin of the eyes is 

 deeply incised, the ocelli are normal, the marginal cell 

 of the fore wings is not appendiculate, and there is only 

 one submarginal cell. The body is black, slender, and 

 of mediiun size. 



I have found, in New York, the nests of Trypoxylon 

 frigidum very common in branches of siunac (Fig. 

 1 198), more common than those of any other insect 

 except the little carpenter-bee, Ceratina. The cells of 

 the nests of Trypoxylon are separated by partitions of 

 mud and are stored with spiders. The larva of Try- 

 poxylon frigidum when full-grown makes a very slender 

 cocoon, with the upper end rounded and sometimes 

 slightly swollen, and the lower end blunt and of denser 

 texture than the remainder of the cocoon. 



An extended account of the habits of two other 

 species of Trypoxylon, T. albopilosum and T. rubro- 

 ctnctMm, is given by the Peckhams ('89), who studied 

 these species in Wisconsin. Of special interest are the 

 observations made by these writers on the cooperation 

 of the males and females during the nest -building 

 period. They state as follows. 



"With both species when the preliminary work of 

 clearing the nest and erecting the inner partition has 

 been performed by the female, the male takes up his station inside 



Fig. 1198." — 

 Nest of Try- 

 poxylon frig- 

 idum. 



