German wasp
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 A German wasp, identifiable by the 6 (female) abdomen sections and black antennae
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| Vespula germanica (Fabricius, 1793) |
The German wasp, Vespula germanica is a wasp found in much of the Northern Hemisphere, and introduced to Australia and New Zealand. German wasps are part of the Vespidae family and sometimes mistakenly referred to as a paper wasp because it builds a grey paper nest, although strictly speaking Paper wasps are part of the Polistinae subfamily. It is more commonly known in North America as a yellowjacket.
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[edit] Identification
The German wasp is about ½ inch (13 mm) long, and has typical wasp colours of black and yellow. It is very similar to the common wasp (Vespula vulgaris), but seen head on, its face has three tiny black dots, thought to be horizon detectors. German wasps also have black dots on their abdomen, while the common wasp's analogous markings are conjoint with the black rings above them, forming a different pattern.
[edit] Nests
The nest is made from chewed plant fibres, mixed with saliva. They are generally found close to or in the ground, rather than higher up on bushes and trees like hornets. It has open cells and a petiole attaching the nest to the substrate. The wasps produce a chemical which repels ants and secrete it around the base of this petiole in order to avoid ant predation.
A solitary female queen starts the nest, building 20-30 cells before initial egg-laying. This phase begins in spring, depending on climatic conditions. She fashions a petiole and produce a single cell at the end of it. Six further cells are then added around this to produce the characteristic hexagonal shape of the nest cells.
Once the larvae have hatched as workers, they take up most of the colony’s foraging, brood care and nest maintenance. A finished nest may be 20-30 cm across and contain 3,000 individuals.
Each wasp colony includes one queen and a number of sterile workers. Colonies usually last only one year, all but the queen dying at the onset of winter. However, in mild climates such as New Zealand, around 10% of the colonies survive the winter. New queens and males (drones) are produced towards the end of the summer, and after mating, the queen overwinters in a crack or other sheltered location.
This common and widespread wasp collects insects including caterpillars to feed to its larvae, and is therefore generally beneficial (unless you are a caterpillar). The adults feed on nectar and sweet fruit, and are also attracted to human food and food waste, particularly sodas and meats.
The nests are subject to predation by the Honey Buzzard, which excavates them to obtain the larva. The hoverfly Volucella pellucens and some of its relatives lay their eggs in the wasp nest, and the larva feeds on the wasp’s young.
[edit] Pest status
Along with the closely related common wasp (pictured right) and two species of Polistes, the German wasp is considered to be a pest in New Zealand. It was probably introduced in the late 19th century, but did not appear in large numbers until around 1940.[1] It is common in the beech forest since it is one of the two wasps that feeds on the honeydew exuded by a native scale insect which lives in the bark of the trees. It has a serious effect on the forest ecology since there is less honeydew available for the native birds.
Nests can be destroyed by pouring diesel or petrol into the nest at night and covering the exit over. Watching wasps return to their home at dusk is one method recommended to locate nests.
[edit] References
- ^ Pest Animal Control Bay of Plenty environment report. Retrieved 7 January 2007
[edit] External links
