Each spring, an inseminated female that has hibernated in a woodpile, wall void, or attic insulation etc., will begin a new colony from a golf ball sized nest. The nest begins with a very few individuals that over the course of the summer can grow to the colonies with up to 4000 members. In the early spring (March or April) there are generally no established nests of yellow jackets. Yellow jackets found inside during this time frame are queens that have overwintered in the attic, wall void, etc., and have just emerged from hibernation and are searching for a place to establish a new colony.
Yellow jackets are the most common of the stinging pests. They are recognized by their characteristic yellow and black markings. Several species of yellow jackets inhabit the northwest. They are social insects that live in colonies that can number from several hundred up to 4000 individuals. Depending on the species encountered, nests are found in the ground, suspended in trees, shrubs or from our buildings or in wall voids, attics and crawlspaces. Nests are always made out of paper-like material called carton, and typically have an elongated football shape to them. In the Northwest, yellow jacket nests do not live through the winter.
Yellow jacket activity becomes aggressive during the fall when the nest is producing overwintering queens and the demand for sugar in the colony increases. Everyone has encountered aggressive yellow jacket activity during a backyard barbecue or a picnic. Yellow jackets can sting repeatedly, inflicting a painful sting each time. They will emit an aggregating pheromone which can lead to a mass of yellow jackets attacking. Yellow jacket stings can be dangerous, depending on the person’s sensitivity to it. Sensitivity can increase so that future stings can become life threatening.
Yellow jackets are beneficial insects, but become a problem when their nests are located in close proximity to human activity. Often nests found in wall voids or attics will incorporate the sheet rock into their nests. These situations can become a hazard when the yellow jackets finally “chew” through the sheet rock into the home, when the homeowner hears a noise in the wall and taps on it, only to put their hand right into the nest or when the nest simply is heavy enough to fall through the sheet rock. Hanging nests or ground nests become problems when they are “accidentally” discovered by the homeowner, gardener, or children.