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The German Wasp, Vespula germanica, ranges in length of 12 – 17 mm long (queens may be up to 20 mm) with a blackish brown abdomen and bright yellow stripes. It is very similar to the common wasp. German wasps have strong black markings including an arrow-shaped mark down the middle of the abdomen a black spots on either side. Wings are long and translucent, legs are yellow and antennae black.
German wasps have a range of impacts; economic, health and environmental. They are considered to be an economic pest of primary industries such as beekeeping, forestry and horticulture. They can be a major social pest as they disrupt people’s enjoyment of the outdoors and the operation of some schools. Furthermore they have a painful sting and are a threat to human health.
German wasps are able to eat a variety of food and are opportunistic predators, feeding mostly on other insects. They will collect sugary solutions such as honeydew, and are well known scavengers. In scrubland-pasture habitat in New Zealand, large over wintered colonies account for much of the biomass of prey consumed. High densities of wasp foragers are created causing a local predation pressure on prey and a depletion of carbohydrate sources. The continuous activity of these colonies reduces the opportunity for the prey species to recover.
There are two ways of reducing a local wasp problem — either finding and destroying nests, or using poison bait. Nests can be destroyed by placing a small amount of insecticide powder (such as a permethrin based product) at the nest entrance in dry conditions. The advantage of poison bait is that foraging wasps carry the poison back to the nest. This means you don't have to find nests or approach those that are very large or hard to get at. There has been considerable research on developing effective poison-baits. In New Zealand a poison-bait is commercially available (Rentokil Wasp Bait), but this is not yet available in other countries. Both control methods will only alleviate the problem for the current season and workers foraging for food will reinvade the area. The area will almost certainly be reinvaded next season by queen wasps, which can fly up to 30 kilometres in their search for suitable nesting sites.