European wasp, German wasp, German yellowjacket
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.
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.
Vespula germanica workers are known to be opportunistic predators and scavengers. They are efficient at hunting for small, live food sources and at collecting from large stationary sources. It is believed that the flexibility in V. germanica's foraging behavior is a key factor in their ability to rapidly colonize new areas in a variety of ecological environments. As scavengers, V. germanica are forced to make numerous trips between the location of the food source and the nest, where the larvae are kept and fed. This calls for V. germanica foragers to be adept at relocating earlier food sources.
V. germanica wasps have a diverse diet. They are known to eat carrion, live arthropods (including spiders), fruit, honeydew, and processed human food and garbage. They are opportunistic scavengers and hunters able to obtain food from a variety of different sources. For example, many Vespula species have been observed feeding on dead honey bees (Apis mellifera) found outside the beehive entrance in the late summer. This flexibility in diet is beneficial, because V. germanica must often compete for resources with native biota in areas it invades.
Vespula germanica queens are typically polyandrous. The queens mate with a moderate number of males, usually between one and seven, with no optimal number of mates. In addition, mating events are independent of each other, which discredits the hypothesis that queens terminate mating behavior after mating with a male that possesses an optimal set of attributes.
V. germanica workers are unable to mate and so incapable of producing diploid offspring. In some nests, however, the workers produce haploid male offspring from unfertilized eggs. Worker reproduction has been documented in other Vespula wasp colonies, but usually only after the death of the queen. However, workers of V. germanica have been found reproducing in the presence of a queen.
