Cooler weather triggers wasp risk

With the cooler weather and frosts arriving, European wasp activity may decrease but the life of a queen is just beginning.

Frosts, along with continuous cold weather, trigger the release of up to 100 fertilised queens from European wasp nests. These queens could each establish new nests in the spring. By alerting the appropriate authorities and pest controllers to the presence of a nest, members of the publics can assist in reducing the numbers of this introduced pest.

In addition to queens being released, Australia’s mild winters can sometimes allow wasp nests to survive over the winter period and the number of wasps in these nests can grow to tens of thousands.

The treatment of this season’s nests before the release of new queens will mean fewer wasps to deal with next year. Locating nests can be difficult, because European wasps will conceal them in a hidden cavity in the ground, in retaining walls or inside a wall or roof cavities. Nests have also been found in unused machinery, sheds and cupboards. The presence of wasp activity around a hole or crack is the most common way nests are identified.

Canberra Urban Parks and Places (CUPP, an ACT Government body) set up an experimental trial this past summer and autumn involving the placing of meat baits laced with insecticide where a nest cannot be located and wasp densities are high.

Results have shown promising rates of nest kill in SA, Tasmania and the ACT using this technique. However, this method is not yet available to householders. The current CUPP trial is coming to a close with the cooler weather, but trials will resume next season.

European wasps are attracted to food scraps and meat products to feed their grubs. Basic hygiene is required to prevent them from scavenging, so ensure pet food and dog bones are not left out. Don’t drink directly from cans or bottles when outdoors. Use a glass or straw.

If you suspect a nest, keep away from it. The European wasp has a nasty sting which it will use to defend the nest. Call a pest control company with environmental authorisation to have it treated and if possible removed. If the nest is on Government land, notify your council or if you live within the ACT call CSIRO Entomology on 6246 4263.

For more information:

Michelle Michie, 02 6246 4263
CSIRO Entomology Insect Identification and Advice Office

Media assistance:
Julie Carter, 02 6246 4040