296 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loe 



Trigonalids have a peculiar life history which has been reviewed for 

 several species by Clausen (Entomophagous insects, pp. 56-61, 1940). 

 Their minute and very numerous eggs are laid at random on foliage 

 and subsequently eaten by caterpillars or sawfly larvae. In the 

 case of the species which are secondary parasites of caterpillars, the 

 eggs hatch in the gut of the caterpillar and the trigonalid larva 

 enters the body of the caterpillar to attack an ichneumonid, larvae- 

 vorid, or other parasitic larva. Those species parasitizing social 

 Vespidae presumably find their host when caterpillar prey containing 

 trigonalid larvae are brought to the nest as food for the young. 

 Individuals of the various species tend to vary considerably in size, 

 an indication that they have a wide range of hosts. The species 

 Lycogaster pullata has been reared as a parasite both of Enicospilus 

 americanus (Ichneumonidae) and of Rygchium rugosum (Vespidae), 

 indicating an exceptionally versatile host adaptability. 



Most of the specimens studied are in the U. S. National Museum 

 (USNM). The locations of specimens in other institutional collections 

 are indicated (in parentheses) by the name of the city in which they are 

 stored. 



Key to the Nearctic genera of Trigonalidac 



1. Postscutellum roughly pyramidal, the apex bifid; legs of female each with a 



single trochanter 4. Bareogonalos 



Postscutellum not pyramidal, of normal shape, not elevated; legs of female 

 each with two trochanters 2 



2. Propodeal foramen bounded dorsally by a carina or ridge that is evenly curved; 



second tergite not punctate; second sternite of female without a tooth. 



1. Orthogonalys 



Propodeal foramen bounded dorsally by a carina or ridge that is sharply angled 



medially; second tergite punctate; second sternite of female with a strong 



median apical tooth 3 



3. Antenna slender, the median segments about 2.0 as long as wide; male antenna 



with tyloids; occipital carina not joining the hypostomal carina, reaching the 



mandible; third sternite of male simple 2. Poecilogonalos 



Antenna thick, the median segments about 1.6 as wide as long; male antenna 

 without tyloids; occipital carina joining the hypostomal carina; third sternite 

 of male with a strong transverse groove 3. Lycogaster 



Genus Orthogonalys Schulz 



Orthogonalys Schulz, Hymenopteren-Studien ... p. 76, 1905. Type: Orthogon- 

 alys holivana Schulz. Monobasic. 



Orthogonalos Schulz, in Wytsman, Genera insectorum, fasc. 61, p. 8, 1907. 

 Emendation. 



Tapinogonalos Schulz, in Wytsman, Genera insectorum, fasc. 61, p. 14, 1907. 

 Type: Trygonalys pulchellus Cresson. Designated by Viereck, 1914. 



Noteworthy generic characters in addition to those in the key are: 

 Flagellum long and slender, in the male without tyloids; abdomen 

 smooth, impunctate; apical margin of second to fifth tergites often 



