The German yellowjacket is a void nesting species found throughout most of the northeastern United States, into Canada and down the Pacific coast into California. In addition to its native lands in Europe, it is found in Chile, Argentina, New Zealand and Australia. Although it is primarily a ground nesting species in Europe, Australia and New Zealand, in North America it usually is found nesting in voids within buildings. It is very common in urban and suburban settings, but is also found in rural buildings. Vespula germanica, an invasive (non-native) species, will aggressively defend its nest and can sting repeatedly. The stings are painful and for sensitive/allergic individuals can pose a serious health risk.
German yellowjacket nest in Pennsylvania attic.
V. germanica workers, all sterile females, are approximately 13 mm (1/2 inch) in length; queens are slightly larger - up to 18 mm. The yellowjacket is colored in black and yellow and the abdomen typically has a small spade-shaped black mark on the first abdominal segment and a series of black spots down both sides from the second to the fifth segments.
Although most of the social wasps such as yellowjackets and paper wasps have annual nests (the colony dies each autumn), the German yellowjacket is known to occasionally reuse previous year's nests. It is unclear how often this occurs, but given the large size of nests found in attics it probably happens more often than previously thought. In New Zealand, where they nest in the ground, a perennial nest was excavated that was 14 feet in length and 5 feet wide. The author has seen a nest in an attic in the Washington D. C. metropolitan area that was approximately 5 feet wide and 3 feet deep. Overwintering, fertile queens begin searching for potential nest sites in the spring. They build a small nest with a few cells and forage for food to feed the first generation of workers. After the emergence of the first brood, these workers take over the duties of foraging for food, feeding the larval yellowjackets and increasing the size of the nest.
Overwintering German yellowjacket queen.
German yellowjackets are notoriously defensive of their nests and will chase other animals away - frequently following for long distances. These colonies can reach into the thousands of individuals late in the summer or early fall and their presence near to people make them a potential danger.
For treatment of German yellowjackets in wall voids of buildings, we advise the use of professional pest control services. Be certain not to plug the yellowjacket entrance because they may chew through interior wall coverings in an attempt to escape and enter the living area or your home. There is evidence that this insect may also attempt to create a new entrance/exit when liquid insecticides are sprayed into the entry. Therefore, to repeat, it is wise to contract with a pest management professional (pest control company) rather than attempting to do this yourself.
Authored by Steve Jacobs
April 2010 Revised February 2015