Bug Spotlight!

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U.C. Riverside
Department of Entomology
Photo by: Rick Vetter (wasp)
 Rick's Mom (aerial nest)
P. Kirk Visscher (bottom photos)
Yellowjackets (Hymenoptera: Vespidae) by Rick Vetter

 Although yellowjackets have stocky "bee-like" bodies (upper left), they are indeed wasps. Most wasps are solitary; however, yellow jackets are eusocial, meaning they have a single queen who lays all the eggs and many sterile female workers who do all the work to build the nest and maintain the brood. There are several species of Vespula and Dolichovespula wasps in southern California. Members of the Vespula vulgaris group (V. germanica and V. pensylvanica) are both insectivorous and scavengers; hence, they are nuisance wasps that bother us at picnic tables and attack our pets' food. Other species (V. sulphurea, D. arenaria) are insectivorous only and are beneficial (at least to humans ... but not to bugs). Yellowjackets, like their larger hornet cousins, make a paper nest of dead plant fibers. The foundress queen, working alone in spring, builds a nest in an abandoned rodent burrow (subterranean) or in a tree or under the eave of a home (aerial nest - top right). When the first workers emerge, they take over the foraging and the queen stays in the nest, laying eggs, until she dies in the autumn. In normal situations, the colony grows to about the size of a bowling ball with about 13,000 cells (lower left, as seen through an observation hive at mid-season) and rears males and new queens in the fall. They mate outside of the nest, after which males die and the new queens disperse for the winter, waiting for spring to start the cycle again. On rare occasion however, daughter queens may remain behind in the nest during the winter, 5 to 70 of them start laying eggs the following spring and the nest is referred to as perennial. With many queens laying eggs, the nest can grow to tremendous proportions (lower right). This perennial nest, removed from UCR's Agricultural Operations was estimated to have 200,000 cells.


2006  ERM-UC Riverside