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• Yellow Jacket

Vespula spp.

Yellow jackets are a species of wasp found worldwide, with about 16 species occurring in the United States. Two of the more frequent found in the Pacific Northwest are the Western yellow jacket and the German yellow jacket.

Yellow jackets are recognized by the distinct yellow and black markings in a banded pattern along the abdomen. They do not have a narrow waist between the thorax and abdomen. They are social bees and live in nests or colonies. A typical worker yellow jacket is about 1/2 inch long (12mm), while queens are about 25% larger (typically 3/4 inch (19mm) long). Workers are sometimes confused with honey bees; however, unlike a honeybee the yellow jacket does not have a 'fuzzy' dense tan-brown hair covering its body for carrying pollen (although they are considered minor pollinators when traveling from flower to flower).

Only inseminated queen's over-winter. This is done in sheltered areas such as hollow logs, stumps, under bark, in leaf debris, soil cavities, and man made structures (attics, wall voids, under porches and eaves, etc). Over-wintering queens may sometimes enter a living space in the winter in search of warmth, or in the spring when looking for a nesting site. The queen will emerge late spring or early summer and select a site, and then build the small paper nest using chewed up cellulose material. Nests are completely enclosed with the exception of a small opening or entrance at the bottom. Nests are guarded at the entrance to protect the colony. Nest size can reach up to the size of a basketball by the end of the season. The nest will originally consist of 30-50 cells and lay 1 egg per cell. After approximately 30 days, the first of the workers are hatched and take over building up the nest, while the queen continues to lay eggs in those new cells. Nest sizes can vary from 300 to 120,000 cells (the average being 2,000 to 6,000 cells) and contains 1,000 to 4,000 workers at its peak. As the season progresses, larger reproductive cells are built in which new queens will be reared (males are usually reared in the old worker cells as opposed to the new reproductive cells). At this point, the nest is in the declining phase. The inseminated queen will again winter over and survive, while the workers, males and founding queens will all die. German yellow jacket nests tend to remain active somewhat longer into the season than the Western yellow jacket. Existing nests are rarely used again.

Yellow jacket adults seek out foods high in sugars and carbohydrates (fruits, flower nectar, etc) while the larvae feed primarily on proteins (insects, meats, fish, etc). Larvae are fed by the adults chewing and conditioning the high in protein foods and feeding it to them. In turn, the larvae produce sugars from those proteins which provide a food source for the adults. This act is called 'trophallxis' In late summer workers are well known for being picnic spoilers due to forging for foods ranging from meat, fruits, soda pop, and human garbage to fill the sugar requirements that the nest no longer produces.

Yellow jackets have a lance-like stinger with small barbs, and they can sting repeatedly (unless the stinger becomes lodged and pulls free from the body of the wasp). They can "mark" aggressors and can pursue them if provoked. The sting of a yellow jacket can be dangerous if the victim receives a large number of multiple stings or if the victim is allergic.

Important preventative measures include:

1. Remove available food sources such as sugars, proteins and pet foods. Any food or beverage spills should be cleaned up as soon as possible. Keep garbage can lids well sealed. Items such has hummingbird feeders should be removed or kept well sealed.
2. Seal cracks and openings at awnings, roofs and siding. Openings can allow a safe harbor for colony nests or over-wintering queens.

While these preventative measures may help prevent an infestation, if a colony has an established nest, a call to Long Pest Control can develop an Integrated Pest Control program to eliminate the sightings and provide an environment free of unwanted pests year round.