Media Release

This huge nest uncovered at Stirling in the Adelaide Hills is one example of "overwintering". Full Image (411.53K) Worker wasps building a nest. Full Image (495.99K) Wasps. Full Image (264.51K)

Tuesday, 7 August 2001

WASP experts at Adelaide University believe European wasps may become a bigger problem during winter.

In theory, European wasps are meant to hibernate during winter, but that's not always the case.

"European wasps are a well-known summer pest, disrupting outdoor events such as barbecues and picnics during the warmer months. People don't expect to be pestered by wasps during the depths of winter, but it can and does happen," said Dr Andy Reeson (Department of Applied & Molecular Ecology).

Dr Reeson is part of a team of European wasp researchers at Adelaide University's Waite Campus. The team is hoping to find suitable biological controls for European wasp.

He said the wasps' activity was normally reliant on European-style seasonal changes.

"A typical European wasp nest is started in the spring by a single queen emerging from hibernation. She raises the first worker wasps herself, which then help her raise more workers, and so the nest grows through the summer. Come the autumn most workers die out while the newly born queens search for a warm, dark place to hibernate.

"This life cycle evolved in the wasps' native range of Europe and north Asia. Now introduced into Australia, our relatively mild winters have enabled some wasps to break free from an annual cycle and remain active throughout the year. While most nests still die off by around mid-June, a small proportion survive through the winter and on into the next summer," Dr Reeson said.

These nests can reach considerable sizes and can contain tens of thousands of wasps--one such nest dug up in the Adelaide Hills was so large, it was too heavy for Dr Reeson to lift!

"The success of these 'overwintered' nests suggests that it is a habit that is likely to spread, which might result in wasps becoming a more continual nuisance," he said.