Symmorphus cristatus

Taxonomy

This species of wasp is in the family Vespidae and the sub family Eumeninae. Eumenids are solitary nest building wasps that stock their nests with many individuals of some species of leaf-eating arthropod prey like caterpillars. As such, they can be helpful to gardeners. There are many species in North America.

Description

Eumenid wasps have a stereotypical “wasp” look to them, but they are solitary and not aggressive like social wasps that are found in the family Vespidae. They are generally black with yellow bands and markings. At rest, their wings fold longitudinally and may appear very thin. They range in size from very small to medium. Symmorphus cristatus is a small wasp that looks similar to the more common Symmorphus canadensis.

Nest Structure

Eumenids are solitary-nesters, each female builds her own nests. They typically use mud or agglutinated sand to build their nest cells and plugs. Frequently plugs have a smooth outer surface. This is in contrast to the bee Osmia lignaria that also uses mud, but tends to have chunkier rougher looking nest plugs. Eumenids stock their nests with paralyzed prey, as is typical of solitary nesting wasps. Prey choices include caterpillars, beetle and moth larvae, including leaf mining beetles and moths and garden or crop pests. Symmorphus cristatus is known to nest in borings in wood and sumac stems. They stock nests with larvae of Chrysomelinae beetles. (Krombein 1967,1979).

Hole Sizes

Symmorphus cristatus nest in column 3 (1/8 - 3/16") holes in Bee Atlas blocks.

Voltinism

Possibly multivoltine. Eumenids can have 2 generations per year in Minnesota.

Activity Period

Early summer into early fall.

References

Buck, Matthias. 2008. Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region. Canadian Journal of Arthropod Identification. Accessed from http://www.biology.ualberta.ca/bsc/ejournal/bmc_05/bmc_05.html.