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Yellow Jacket-Wasp (Vespula)
admin - 07/01/2015

Yellow Jackets are approximatley 1/2" long, while queens are somewhat larger at 3/4" in length. They are black and yellow in color with distinguishing patterns on their abdomen, which identify the species. The western yellow jacket, Vespula Pensylvanica, is the most common species in California. This and most other yellow jackets build their nest undergound in abandoned animal burrows. They may also nest in wall voids and attics where, during the winter when food is scarce and the temperature outside cools, they may begin to forage for food indoors. Other species build their nests in trees and other open areas.

In the spring, an impregnated female, the queen, will build a small nest in which she lays her eggs. The nest is created from cellulose gathered from tree bark, dried plant materals, or other sources, mixed with saliva, and formed as the hexagonal cells or the larvae. After the eggs hatch, the larvae are very dependent on the queen for food. The larvae need protein, so the queen feeds on a sweet liquid secreted from the larvae. After pupation, the larvae become the adult workers. They expand the nest and take over the job of foraging for food and feeding the larvae. A nest lasts one to two years and may contain up to 15,000 yellow jackets.

Yellow jackets are beneficial insects; they contribute to the control of many garden pests. They become a nuisance when their foraging brings them close to people. They are unpredictable and may or may not attack people when disturbed. Their stingers are not barbed which make them able to sting multiple times. Certain species are more aggressive than others are.


Title Date
Honey Bee, European (Apis mellifera)  07/01/2015
Yellow Jacket-Wasp (Vespula) 07/01/2015
Roof Rat  05/08/2014
House Mouse (Mus Musculus)  05/07/2014
Carpenter Ant (Camponotus)  05/07/2014