Superfamily SPHECOIDEA 1665 



Genus CROSSOCERUS Lepeletier and Brulle 



This large genus contains a number of subgenera and numerous species. Some of the sub- 

 genera are ground-nesters, others nest in pre-existing burrows or cavities in wood, or construct 

 their own burrows in soft pith of herbs and stems or in rotten wood. Most species prey upon 

 small Diptera, but some prey upon Homoptera, Trichoptera, Microlepidoptera, Hemiptera, and, 

 rarely, Mecoptera and Ephemeroptera. So far as known, our North American species do not 

 store this entire range of prey. 



Taxonomy: Pate, 1944 (1943). Lloydia 6: 267-271 (key to subg.). — Leclercq, 1968. Soc. Roy. 

 Sci. Liege, Bui. 27: 99-100 (key to xylicolous subg.). 



Genus CROSSOCERUS Subgenus CROSSOCERUS Lepeletier and Brulle 



Crossoceriifi Lepeletier and Brulle, 1834. Soc. Ent. France, Ann. 3: 763. 



Type-species: Crabro scntatus Fabricius. Desig. by Westwood, 1839. 

 Crabro subg. M icrocrabro Saussure, 1892. In Grandidier, Hist. Nat. Madagascar 20: 574. N. 

 syn. (R. C. Miller). 



Type-species: Crabro (M icrocrabro) micromegas Saussure. Monotypic. 

 Stenocrabro Ashmead, 1899. Canad. Ent. 31: 216. 



Type-species: Crabro planipes Fox. Grig, desig. 

 Synorhopal 1(7)1 Ashmead, 1899. Canad. Ent. 31: 218. 



Type-species: Crabro decorits Fox. Grig, desig. 

 Ischnolynthiis Holmberg, 1903. Mus. Nac. Buenos Aires, An. 9: 472. 



Type-species: Ischnolynthus foveolatHs Holmberg. Monotypic. 

 Crossocerus subg. Yiicliiha Pate, 1944 (1943). Lloydia 6: 272. N. syn. (R. C. Miller). 



Type-species: Crossocerits (Yucliilia) xanthochilos Pate. Grig, desig. 



Relatively little is known of the biology of members of this subgenus. Some species are known 

 to nest in the ground; this is substantiated by some of the morphological features of the females. 

 However, a few species are known to nest in pre-existing burrows in wood above the ground. It 

 is possible that many species utilize pre-existing burrows, modifying them as required as nesting 

 sites. If this is so, perhaps the few species which have been reported as nesting in wood may be 

 found eventually to nest in the ground also. 



chromatipus Pate. Nev., Calif., Greg., Wash. 



Crabro pictipes Fox, 1895. Amer. Ent. Soc, Trans. 22: 187. 6. Preocc. 

 Crossocenis (Crossocerus) chromatipus Pate, 1944 (1943). Lloydia 6: 280. N. name. 

 decorus (Fox). Nebr., Colo., Utah, west. Tex. to south. Calif., south in Mexico to Chiapas. 

 Ecology: Nests in sand, clay, and softer spots of rocky root-shrouded stream banks; 

 pre-existing burrows of other insects are used and new side branches are constructed, 

 resulting in twisted burrows 8.5-15.0 cm long, weakly branched, with tight clusters or 

 linear series of cells grouped around end of burrow; up to 9 cells per nest with 8-29 

 prey per cell. Prey: Chloropidae, Pipunculidae, Stratiomyidae, Ceratopogonidae, 

 Empididae, Sciaridae, Dolichopodidae, Tachinidae, SimuHidae, Tephritidae, Agromyzidae, 

 Chironomidae. 

 Crabro decorus Fox, 1895. Amer. Ent. Soc, Trans. 22: 200. 9. 



Biology: Cockerell, 1898. Davenport Acad. Nat. Sci., Proc 7: 148 (nest). —Smith, 1908. Nebr. 

 Univ. Studies 8: 395 (nest). 

 elongatulus elongatulus Vander Linden. Transit, and U. Austr. Zones, N. S., Que., Gnt., Maine 

 to Va. west to Utah and Wash; Palaearctic south of Arctic Circle including North 

 Africa; adventive in Argentina. Ecology: In Europe it is recorded as nesting in soil or 

 wood, and sometimes in pre-existing burrows of wood-boring insects; nests have been 

 found in such odd habitats as soil clinging to roots of fallen trees, old mortar of 

 buildings, crevices in stone walls, and in cracks of rock outcrops; communal nesting has 

 been reported once. Parasite: In Europe a species of Macron ychia has been recorded. 

 Prey: Chloropidae, Lauxaniidae, Scatopsidae, Cecidomyiidae, Empididae, Phoridae, 

 Dolichopodidae, Syrphidae, Agromyzidae, Milichiidae, Tachinidae, Ephydridae, 



