178 



HYMENOPTERA. 



or it is indented, as in Mutilla. The tongue is shorter than usual. 

 The sides of the thorax contract in width, both before and be- 

 hind. The meso-scutum is squarer than usual, while the meso- 

 scutellum is much narrower and longer, and the propodeum is 

 squarely truncated behind, thus presenting a full convex surface. 

 The abdomen is not much longer than the rest of the body, be- 

 ing shorter than usual. In all these characters this family shows 

 its affinities to the Ants. The wings are very dissimilar in the 

 different genera. In Myrmosa the neuration closely approaches 

 that of Sapyga, while in the larger, more acute primaries of 

 Mutilla, and especially in the short outer costal cell, and short 

 open pterostigma, the latter genus differs from the others. 



The male of Sderoderma closely mimics the Procto- 

 trypidce, the veins of the wings being absent, w T hile the 

 form of the head and abdomen also reminds us of some genera 

 in that family. The wingless female is very different, having 

 more of the form of Mutilla, with a large oblong head and long 

 acutely conical abdomen. The species are minute and rarely 

 met with. S. contracta Westwood is found in "Carolina." 



In the female Methoca the eyes are very long, and the seg- 

 ments of the abdomen are widely separated, much as in the 

 ants. Methoca Canadensis Smith is shin- 

 ing black, and slightly villose. 



The species of Myrmosa may be known 

 by the very short clypeus, the broad ver- 

 tex, and the rings of the abdomen of the 

 male being unusually contracted. The 

 abdomen of the female is cylindrical, 

 about twice as long as broad, and thickest on the second ring. 

 The rings are densely hirsute on the hinder 

 edge. Myrmosa unicolor Say (Figs. 107, 

 male ; 108, female) is widely distributed. AVe 

 have taken this species in Maine, while sex- 

 ually united, early in June. The wingless 

 female is like an ant, and is pale reddish on 

 the thorax and basal ring of the abdomen, 

 and the antennae and feet are concolorous, while the head and 

 remaining abdominal rings are much darker. It is .20 inch 

 long. The male is .28 inch long and entirely black. 



Fig. 108. 





