Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region
Matthias Buck, Stephen A. Marshall, and David K.B. Cheung
Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
Species recognition. Monobia quadridens is the only eumenine wasp in eastern Canada with a single, broad, apical fascia on tergum 1 but otherwise black metasoma. Euodynerus bidens, which occurs in the eastern U.S. as far north as Minnesota and New Jersey, strongly resembles M. quadridens in size and colouration but can be distinguished by the evenly rounded posterolateral margin of the tegula (bluntly angled in M. quadridens), truncate clypeal apex without distinct lateral teeth (shallowly emarginate with distinctly projecting lateral teeth) and evenly rounded base of sternum 2 (abruptly angled).
Variation. Fore wing length 11.0–14.5 mm (♂♂), 14–18 mm (♀♀). The following ivory markings are sometimes present: a small spot on male scape, a pair of lateral (rarely paramedian) spots on scutellum (rarely an almost complete transverse band), small spots on dorsal surface of propodeum (especially in males), traces of apical fascia on male tergum 2, and a small spot near base of fore tibia dorsally.
Distribution. Canada: southern Ontario. Eastern U.S.: NH to FL, west to WI, KS, NM (Krombein 1979). Northern Mexico: Tamaulipas, Nuevo León (Porter 1981, Rodríguez-Palafox 1996). The occurrence of this species in Canada was apparently never mentioned in the literature, but identified material has been present in Canadian collections for a long time.
Biology. Nests in various types of cavities like abandoned carpenter bee tunnels, hollow stems, old mud dauber nests and rarely in old burrows of ground-nesting bees. Nest partitions and closing plugs are made of mud or agglutinated sand (Krombein 1967). Prey consists of Microlepidoptera caterpillars of Pyralidae (Phycitinae, Epipaschiinae), Crambidae (Pyraustinae), Elachistidae (Stenomatinae), Amphisbatidae, Gelechiidae and Tortricidae (Krombein 1967, 1979).