Psyche 
[September 
68 
margin ; palpi strong, about 80 /jl long, terminating in three large 
sensory cones; galeae more slender, about .7 as long as palpi, ter- 
minating in a single large sensory cone (Fig. 4). Labial palpi 
slightly shorter than maxillary palpi, slightly exceeding the blunt, 
paired spinnerets; oral surface of prementum with a patch of small 
spinules. 
Discussion. — Despite the larrine-like appearance of adults of this 
wasp (giving rise to the specific name larroides) , the larvae bear no 
resemblance to those of Larrinae. The presence of an antennal 
papilla, the terminal anal opening, the form of the mandibles, and 
several other features indicate that Heliocausus belongs in or near 
the subfamily Nyssoninae. In fact, it runs readily to Nyssoninae 
in my table of subfamily characters (Evans, 1959, p. 168), and in my 
artificial key to genera (ibid, p. 1 7 1 ) the genus keys out near 
Sphecius and Gorytes (Nyssoninae, Gorytini). The mandibles, 
labrum, and maxillae are especially similar to those of Gorytini. It 
should be added that Dr. Fritz found II. larroides preying upon leaf- 
hoppers, a distinctive (although not exclusive) gorytine attribute. 
On the other hand, there are certain larval features not shared 
by any known Gorytini: the oral surface of the prementum is 
spinulose (as in Bembicini), the opening between the spiracular 
atrium and subatrium is unarmed (as in Philanthinae and a few 
primitive genera of Nyssoninae), and the apical abdominal segment 
is slender and protuberant (as in Philanthinae). I regard the 
Nyssoninae and Philanthinae as having had a common origin inde- 
pendent of other subfamilies (ibid, p. 183). While on the whole 
Heliocausus has many more larval characters in common with the 
Nyssoninae, the presence of some philanthine characters and some 
in common with generalized Gorytini suggests that the group may 
be a relict of a primitive nyssonine-philanthine stock. Manfredo 
Fritz informs me that he and Prof. H. Toro of Valparaiso have 
come to somewhat similar conclusions on the basis of adult structure ; 
their paper is soon to be published in the Ann. Mus. Hist. Nat. 
Valparaiso. 
Reference Cited 
Evans, H. E. 
1959. Studies on the larvae of digger wasps (Hymenoptera, Sphecidae). 
Part V: Conclusion. Trans. Amer. Ent. Soc. 85: 137-191. 
