European Wasp a Danger to Australia's Biodiversity

CANBERRA, Australia, January 11, 2005 (ENS) - Australia has been invaded by a wasp from Europe that government scientists say is posing a threat to the island continent's biodiversity, particularly moths and butterflies. High numbers of wasps can denude an area of other insects and spiders.

The Commonwealth scientific research branch, CSIRO, is working with Canberra Urban Parks and Places to alert Canberra residents about the harmful effects of the European wasp, the two organizations said today.

As an invasive species the European wasp, Vespula germanica, has what CSIRO called "a drastic effect on Australian biodiversity."


European wasp queens are usually only seen in winter and spring. (Photo courtesy CSIRO)
By the end of the Australian summer, each European wasp nest may contain several thousand individuals. The larvae complete their development after being fed a diet which mainly consists of other insects which the workers catch and kill. This means that each European wasp nest has the potential to remove several thousand native insects - often the caterpillars of moths and butterflies - from the environment.

"This can have a devastating direct effect on biodiversity, while also indirectly disrupting ecosystem function," CSIRO said in a warning statement.

"As with many introduced species there are few if any native predators which would naturally keep wasp populations under control," said Kim Pullen of CSIRO Entomology. "These insects are increasingly an environmental and economic pest to Australia."

European wasps are now found in many southeast Australian vineyards where they cause crop damage and threaten vineyard staff.

The first European wasp recorded in Australia was in Tasmania in 1959, and the wasps are now common there. On the mainland the European wasp was reported in Melbourne in 1977 and in Sydney in 1978. The wasp is now established in southern Victoria and in the Sydney area and has been seen in rural New South Wales.

Since early 1985 a number of European wasp nests have been found in Canberra. These were destroyed by the Australian Capital Territory (ACT) Parks and Conservation Service in an effort to prevent the wasp becoming established in the ACT.

The European wasp is about the size of a honeybee, but thinner, and can be distinguished from other wasps by its yellow, not orange, and black color, with black arrowhead-shaped markings pointing backwards along the top of the abdomen and black spots on either side. Wings are long and transparent, antennae black and legs mostly yellow.


The nest of the European wasp is rarely seen out in the open. (Photo courtesy CSIRO)
These social wasps form large colonies. The queen spends the winter hibernating under shelter and emerges in spring to establish a new nest. Her first offspring are workers which take over nest chores. A papery nest is made by mixing saliva with wood fibers and it grows over summer to reach the size of a football.

The nests are nearly always concealed underground or in a roof or wall cavity or hollow tree.

The European wasp can inflict a series of painful stings when its nest is disturbed. Multiple stings or a sting in the throat can be dangerous or fatal as the swelling associated with the sting can block the victim's airway.

Pullen said European wasps thrive in urban areas, and their liking for fruit, meat and sweet foods and drinks means they often turn up at barbecues and picnics. Their sting is painful and unlike honeybees, they can use it repeatedly. Some people have a severe allergic reaction to the sting.

Pullen warned that if wasps are about, people should not drink directly from cans or bottles, and ensure children do not do so. "Wasps enter soft drink cans searching for food and can easily be swallowed with potentially nasty consequences," he said.

"The only effective way of reducing wasp numbers is by destroying nests, but this is a hazardous job best left to an experienced pest control operator," Pullen said. CSIRO Entomology can provide information on appropriate methods, he said, "for those householders brave enough to try."