HYMENOPTERA. 657 



We have found the nests of Trypoxylon frigidum (Try- 

 pox'y-lon frig'i-dum) very common in branches of sumach 

 (Fig. 785), more common perhaps than those of any other 

 insect except the little carpenter-bee, Ceratiua. The cells 

 of the nest of Trypoxylon are separated by partitions of mud, 

 and the pupa 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. The adult insect is very slender 

 and lacks the yellow bands on the abdomen, possessed by 

 most members of this family. 



Superfamily VESPINA (Ves-pi'na). 

 The True Wasps. 



All members of this superfamily are winged, and when 

 at rest fold their wings lengthwise like a fan. In this last 

 respect they differ from all other Hymenoptera except a 

 single genus of Chalcis-flies, Leucospis (Leu-cos'pis). The 

 prothorax is prolonged backwards on each side to the 

 base of the front wing ; the eyes are kidney-shaped ; and the 

 legs are not formed for burrowing, being free from spines and 

 bristles. 



Three families are included in this superfamily ; these 

 can be separated by the following table : — 



A. Antennae clavate or knobbed at tip. p. 657 M ASARiDiE. 



AA. Antennae filiform or nearly so. 



B. Tibiae of the middle legs with a single terminal spur; tarsal 



claws armed with a tooth, p. 658 Eumenid^;. 



BB. Tibiae of the middle legs with two terminal spurs; tarsal 

 claws simple, p. 660 VESPlDiE. 



Family MASARID.E (Ma-sar'i-dae). 



The Guest-wasps. 



This is a small family of which only seven species are 



known to occur in the United States. These are found in 



Texas and the far West. As yet nothing is known regarding 

 43 



