Anyone who's eaten outside in late summer knows how quickly this wasp can crash your picnic or tailgate party. Often mistaken for bees, German yellow jackets belong to a group of social wasps that cooperate to build and defend their queen and colony, according to UW-Madison entomologist Robert Jeanne. A German yellow jacket nest starts in spring with a single queen. By September a nest may number 3,000 or more foraging workers, says Jeanne. As colonies grow during summer, the numbers of German yellow jackets zooming around farm markets, picnic grounds, and football games become a serious problem.
Yellow jackets are aggressive when threatened.
Unlike a honeybee, which stings only once, a yellow jacket can sting repeatedly. The sting can be life-threatening to those who are allergic to it. A native of Europe, the German yellow jacket reached Wisconsin in 1979. Its arrival sparked a sharp increase in emergency room treatments for stings. Foragers return to their nest with food, which they feed to adult and larval wasps.