The Biology of the Vespidae, Pompilidae, and Sphecidae (Hymenoptera) from Trap Nests in Northwestern Ontario

Uni- and bi-voltine strains of the eumenine wasps, Rygchium leucomelas (Sauss.), Ancistrocerus catskill albophaleratus (Sauss.), A. c. catskill (Sauss.), and A. tigris tigris (Sauss.) occur in the Black Sturgeon Lake region of Ontario. Another eumenine, Symmorphus cristatus cristatus (Sauss.), is univoltine. All the eumenids plug and divide their nests with partitions of clay. Generally, females emerge from cells larger than those of males. A double partition with an intervening space between cells is introduced occasionally in summer-generation nests and frequently in overwintering-generation nests. Generally, individuals of the bivoltine summer generations were predominantly female but overwintering generations were predominantly male.All eumenine wasps, except S. c. cristatus, provision their nests with lepidopterous larvae. A broad spectrum of prey was utilized but at any given time the female wasp shows considerable fidelity in searching for prey on a given host plant.Limited parasitism of the eumenids by the genus Chrysis and the ichneumonid genus Ephialtes was observed. The dipteran Amobia distorta Allen was found in nests of A. c. catskill and R. leucomelas.A single species of pompilid, Dipogon sayi sayi Banks, occupied the trap nests in small numbers. The prey of this wasp consists mainly of spiders in the genus Xysticus.The sphecids include Passaloecus ithacae Krombein, which was common, an unidentified Pemphredon sp., and Passaloecus mandibularis (Cr.). P. ithacae provisioned mainly with aphids of the genus Cinara; Pemphredon sp. utilized C. abieticola; and P. mandibularis preyed upon a wide range of species including several aphids from deciduous trees.Partitions in Passaloecus nests were primarily resin but female P. ithacae often incorporated chips of pith. Cell sizes were frequently out of proportion to the volume of prey and the size of the wasp larvae. Limited parasitism by the chrysidid genus Omalus and the ichneumonid genus Poemenia was noted.