4 U. S. NATIONAL MUSEUM BULLETIN 216 



has been redescribed by the authors (ibid., p. 414). Lethades is a 

 synonym of Trematopygus, a genus of Scolobatinae (see Townes, 

 1945, Mem. Amer. Ent. Soc. vol. 11, p. 484). 



Ischyrocnemis appears to belong in the Scolobatinae and Strongylopsis 

 in the Ephialtini. Heinrich (1949, Mitt. Miinchner Ent. Gesl., vol. 

 25-29, p. 13) has recently referred Alomya to the Metopiinae, basing 

 his opinion, as he has informed us in conversation, on certain mor- 

 phological resemblances and on the fact that Alomya is like Metopius 

 in its habit of buzzing like a wasp when caught. Alomya is an aber- 

 rant genus whose systematic position has long been a subject of specu- 

 lation, but to us seems to belong near Colpognathus, in the subfamily 

 Tchneumoninae, and to represent an extreme development along the 

 evolutionary line leading through Centeterus, to Colpognathus, to 

 Pseudolomya, Megalomya, and Alomya. 



The elimination of the above genera reduces the content of the 

 Metopiinae to a morphologically and biologically cohesive group, 

 recognizable on the characters listed above. Within the subfamily 

 there are several natural groups of genera, to which attention should 

 be called. Pseudometopius, Acerataspis, Chorinaeus, Trieces, and 

 Hemimetopius are related, and differ from other Metopiinae in having 

 the epipleura vestigial, the front and middle tarsal claws pectinate, 

 and the male with six or seven and the female with six well exposed 

 abdominal tergites. These five genera are further divisible into two 

 natural groups as indicated in couplet 3 of the key to genera. Some 

 species of Metopius also have the front and middle tarsal claws 

 pectinate, and Metopius also has seven well exposed tergites in the 

 male and six in the female, but all species of Metopius have well 

 developed epipleura, and the genus appears to be an isolated one. 

 The rest of the subfamily is composed of a loose group of genera, 

 within which is a small distinct subgroup including Triclistus, Cubus, 

 and Colpotrochia. These three genera have a distinctive type of 

 carina between the antennal sockets, a distinctive type of female 

 subgenital plate, and the female abdomen with retracted apical 

 segments. Spudaeus is somewhat similar to these three in the female 

 abdomen and subgenital plate, but does not have the characteristic 

 type of carina between the antennal sockets. The rest of the genera 

 constitute a loose and hardly definable third subgroup, which may be 

 arranged in a series with individual and progressive specialization, 

 leading ultimately to Exoclius as the most specialized genus of the 

 subfamily. 



Biology and Distribution 



The only information on the biology of the Nearctic species of this 

 subfamily is in the data on hosts and ecology on the pin labels of 

 specimens, some field notes and memories about our own collections, 



