German Yellowjackets

Summary

German yellowjackets are invasive wasps that have spread throughout the northern United States, including all of Pennsylvania. They outcompete and displace native yellowjacket species, build nests in and around human structures, and frequently come into conflict with people while foraging for food.

Classification

Family: Vespidae (social stinging wasps)

Genus: Vespula (yellowjackets)

Scientific name: Vespula germanica (Fabricius, 1793)

Common name: German yellowjacket, European wasp

Description

Workers are approximately ½ inch (13 mm) in length, while queens are approximately ¾ inch (18 mm) in length. German yellowjackets are black and yellow in coloration. The abdomen* typically has a small spade-shaped black mark on the first segment and a series of black spots down both sides from the second to the fifth segments (Figure 1).

German yellowjacket nests consist of a series of horizontal combs encased in a paper envelope. The paper is typically grey to brown in color, depending on the source of the wood pulp (Figure 2). In North America, nests are usually in attics, wall voids, and other open areas of structures but may be found underground as well.

Distribution

German yellowjackets are native to Eurasia, including all of Europe except Scandinavia east to western China, much of the Middle East, and North Africa.

However, German yellowjackets have been introduced around the world and are now pests in New Zealand, Australia, southern Africa, parts of South America, and North America.

In North America, German yellowjackets were first detected in New York in 1891. However, they were uncommon until the 1970s, by which point they had become established across much of the Northeast. Since then, they have spread across the northern United States and southern Canada and are found coast to coast. South of Washington, D.C., German yellowjackets are restricted to higher elevation areas of the Appalachian Mountains and are generally absent from the Southeast.

Lifecycle

In their native range, German yellowjackets usually build underground nests. However, in North America, most nests occur in open cavities, especially in the walls of buildings, attics, and similar areas. This propensity of the invasive ecotype for building nests in structures may be one reason that it was able to establish and spread.

German yellowjackets usually build annual nests. That is, an overwintering queen emerges in the spring to start a new nest by herself. Once the first generation of workers emerge, they take over nest-building and foraging duties. The nest continues to grow until the fall, when they usually contain 1,000-3,000 workers. New queens and males then leave the nest to mate. The males die soon after mating while the new queens find a dry, protected place to hibernate through the winter. The nest then declines until the workers and remaining brood die off due to the declining availability of food and the onset of cold weather.

Occasionally, nests in warm areas (either due to a warm climate or because the nest is built in a heated, insulated structure) survive the winter. In these cases, mated queens return to the parent nest and the nest continues to grow into a second season. Such perennial nests can contain hundreds of queens rather than just one and can be gigantic – the largest underground nest, found in Tasmania, was 4 × 4 × 1.5 feet (1.2 × 1.2 × 0.5 m) and weighed more than 200 pounds (90 kg), while the largest aerial nest, found in Australia, was more than 16 feet (5 m) in length and weighed more than 1000 pounds (450 kg). While large, perennial nests are occasionally found in North America, they are not common.

Pest status and impact on native species

German yellowjackets are omnivores. They frequently prey on native insects and scavenge from dead animal carcasses and discarded human food (Figures 3–4). They also feed on carbohydrate sources, such as honeydew from scale insects or spotted lanternflies and sugary foods or drinks (Figure 5). Because of their preference for living in human structures, they frequently forage around trash cans, picnics, fallen fruit, and similar areas and come into conflict with people.

German yellowjackets sometimes attack honey bees. However, attacks generally target individual bees rather than the hive and honey bees usually respond to and repel attacks, so the negative effects of wasp attacks on the overall colony tend to be minimal.

A recent study demonstrated that German yellowjackets have displaced native yellowjacket species in western New York, where they account for more than 90% of yellowjackets captured in urban and suburban areas and nearly 70% of yellowjackets captured in rural areas. While there are no similar studies for Pennsylvania, German yellowjackets are the third most observed species in the state on iNaturalist, after native eastern yellowjackets (V. maculifrons) and southern yellowjackets (V. squamosa).

Control

For detailed information about how to control wasp nests, see the article Getting Rid of Paper Wasps, Yellowjackets, and Other Stinging Insects.

Because German yellowjackets construct annual nests, the simplest method of control is to wait until the first hard frost or two kills off nearby nests.

If more direct control of the yellowjackets is needed, the nest will need to be found, the location of which may influence control options. If a nest is in the wall void of a building, do not cover or close the outside entrance. If the yellowjackets can’t exit the nest, they may chew through interior wall coverings in an attempt to escape and enter indoor living spaces.

If you can access the nest, insecticides applied to the nest or nest entrance may be enough to eliminate the wasps. Insecticidal dusts are usually the best option if the nest is mostly concealed. They can be applied to the nest entrance, and the yellowjackets will track them into the nest as they enter. Dusts remain effective for weeks or months after application and can be moved by the yellowjackets themselves or drift on the air as they are applied.

If a nest is more exposed, aerosol wasp and hornet sprays can be effective. Apply them liberally enough to soak through the paper envelop of the nest, or yellowjackets near the center of the nest will not be killed. Aerosols can drift or overspray easily during application and break down as they dry so lose toxicity quickly. Keep insecticide residues and off-target movement in mind when deciding which type of insecticide fits the situation better.  

If you decide to treat a nest yourself, make sure to wear long sleeves and pants with the cuffs taped and/or tucked into long socks and gloves in order to reduce the chance of being stung. If you are allergic or otherwise unable to treat the nest yourself, contact a professional pest control company.

When overwintering yellowjackets are found in the home in the winter and spring, the most immediate control is to capture and kill the wasp. The best long-term solution is to prevent overwintering wasps from entering the building by sealing cracks in the siding and around windows, pipes, etc, that allow them to enter the wall void in the first place.

Warning. Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.

References

Akre, R.D., A. Greene, J. F. MacDonald, P. J. Landolt, H. G. Davis. 1980. Yellowjackets of America North of Mexico. U.S. Department of Agriculture, Agriculture Handbook 552. 102 pp.

Fearn, S., J. Dowde, D. Maynard. 2015. Record sized perennial subterranean nest of the introduced European wasp Vespula germanica (Hymenoptera: Vespidae: Vespinae) in Northern Tasmania. The Tasmanian Naturalist 137: 49–56. Available online at ResearchGate.

Pusceddu M, I Floris, F. Buffa, E. Salaris, A. Satta. 2017. Agonistic interactions between the honeybee (Apis mellifera ligustica) and the European wasp (Vespula germanica) reveal context-dependent defense strategies. PLoS ONE 12(7): e0180278. doi.org/10.1371/journal.pone.0180278

Warren, R.J., and J. Promowicz. 2025. Non‑native Vespula germanica yellowjackets dominate urban‑to‑rural gradient. Biodiversity and Conservation 34:271–282. doi.org/10.1007/s10531-024-02970-2