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Species of wasp

Vespula germanica, the European wasp, German wasp, or German yellowjacket is a species of wasp found in much of the Northern Hemisphere, native to Europe, Northern Africa, and temperate Asia. It has spread and become well established in many other places, including North America, South America (Argentina and Chile), Australia, South Africa, and New Zealand. German wasps are part of the family Vespidae and are sometimes mistakenly referred to as paper wasps because they build grey paper nests, although strictly speaking, paper wasps are part of the subfamily Polistinae. In North America, they are also known as yellowjackets.

Vespula germanica belongs to the genus Vespula, which includes various species of social wasps that are found throughout the Northern Hemisphere. In North America, these wasps are most commonly known as yellowjackets, but this name also applies to species within the sister genus Dolichovespula. Members of Vespula are often confused with other genera, especially the paper wasp Polistes dominula. Colonies of V. germanica share many characteristics with those of V. vulgaris (common wasp) and V. pensylvanica (western yellowjacket), so they are very often studied together.

The German wasp is about 13 mm (0.5 in) long, has a mass of 74.1 ± 9.6 mg, and has typical wasp colours of black and yellow. It is very similar to the common wasp (V. vulgaris), but unlike the common wasp, has three tiny black dots on the clypeus. To further complicate the issue this only applies to workers. To help with identification, a good practice to observe is to first categorize the wasp as worker, queen, or drone before identifying it as V. vulgaris or V. germanica. Gastral pattern (the black dots or marks on the abdomen) are highly variable and not good characteristics to use in identifying. However, the identification of a wasp as V. vulgaris may be difficult because the normally unbroken black mark on its clypeus can sometimes appear broken (particularly in males) making it look extremely similar to V. germanica.

V. germanica originated in Europe, Asia, and North Africa and can now be found in sections of every continent but Antarctica. It has established populations in North America, South America, South Africa, New Zealand, and Australia. German yellowjackets are known to be especially successful and destructive invaders of new territories. These wasps are polyphagous predators which feed on native arthropods, and because they are able to outdo many other animals for food, they have caused considerable harm to the indigenous wildlife of areas which they have invaded. For a given year, V. germanica disperses at distances of no more than 1000 m, so that their rapid dispersal is likely to be aided by accidental human transport of hibernating queens. This normally leads to a bottleneck effect during the establishment of new populations, which explains the significant genetic differentiation often found among geographically distant populations. The nest is made from chewed plant fibres, mixed with saliva. The majority of nests are found in the soil below ground. A significant portion of nests are found in artificial structures such as attics, and a small portion are found above ground.

A single queen initiates a nest in the spring by constructing an embryonic nest, which contains a series of hexagonal cells. These cells are used to house one wasp through the immature stages of life: egg, larval instar, and pupa. The colony grows rapidly during the summer with a huge increase in worker numbers and nest size. By the end of summer, the rate of growth slows considerably and more males are produced than workers, and the focus is shifted from building small cells to building cells that are 30 40 percent larger. These new cells house the new queens and males. In the fall, the new queens begin hibernation, while the old queens die off and the colony collapses. In some cases, the nests may survive through the winter and reach the next season. If this occurs, the nest will become polygynous and reach a much larger size than in the previous year. Additionally, a significant number of nests in Australia are able to survive the winter, whereas in England none of the nests survive. This demonstrates how V. germanica nests can reach a substantial size in appropriate climate conditions.