Yellowjackets (Vespula, Dolichovespula, Vespa) are a species of vespid wasps. They are generally viewed as aggressive, though truthfully if they do not feel threatened they probably will not sting you.

Yellowjackets are scavengers, and will eat anything from fruit, to meat, garbage, even you. Their bite is quite painful. Yellowjackets can of course also sting. They will sting repeatedly, until they lose their stinger.

The name Yellowjacket refers to the yellow and black stripes that run up their abdomen. Despite the name, not all Yellowjackets are yellow and black. Several species are black and white, but are still referred to as Yellowjackets, which are also known as Eastern Yellowjackets, Common Yellowjackets, or German Yellowjackets.

Like other wasps, the Yellowjacket is a social insect. They build enclosed paper nests underground, in trees, or in other structures above ground.

Each spring, a typical Yellowjacket nest will start with a new queen. The new queen is the only Yellowjacket to survive a cold winter by hibernating. Once the queen wakes from hibernation she will lay 45 to 70 eggs which hatch and become the first generation of workers.

These workers are not naturally sterile like bees, but instead are chemically inhibited from having any offspring by pheromones produced by the queen. If the queen is lost, the workers will produce male offspring. The workers perform all tasks for the hive, including expanding the nest, foraging for food, and protecting it. During the late summer, the colony can grow to the size of 5000 or more individual yellowjackets. During this time of overpopulation, many yellowjackets become aggressive and stinging incidents rise. They must fly further to find enough food for the nest and will often fight workers from other nests, and other animals it views as threats to it's food source.

As autumn approaches males mate with the new queen and leave the nest to die. The remaining workers and the old queen die as the weather gets colder.

The easiest ways to control the yellowjacket population is to not leave food exposed, and tightly cover your garbage. Because yellowjackets are scavengers the presence of both will attract them. Yellowjackets will defend their nest aggressively if attacked, and will often do in swarms, so if you have found a nest it is better to let the exterminator handle it, or if you're feeling adventurous, at night when they sleep.