Wasps as Pests
European wasps prefer to nest around human habitation where they can scavenge food and sweet liquids. Large numbers of wasps can be attracted to picnics and barbeques and interfere with outdoor activities.
School bins in the play ground are often abuzz with European wasps searching for and feeding on food scraps and entering drink cans.
Wasps can sometime be benefical in gardens by removing caterpillars and other such garden pests. However, they make pests of themselves by damaging ripening fruit, and to help reduce the numbers of European wasps in your backyard, the home gardener must continually clear all fruit that has fallen to the ground. European wasps can cause economic loss and problems fruit picking in commercial orchards.
European wasps have caused considerable losses to the honey bee industry in New Zealand, however similar losses have not been recorded in Australia.
Factories and shops processing or selling fruit, cakes or soft drinks often have problems caused by wasps attracted to the smells. The problems occur either when they annoy the workers or if they are accidently incorporated into and contaminate the product.
The European wasp pest problems are greater in newly invaded places, like Australia, rather than in Europe for the following reasons.
When the wasp invades new countries, it leaves behind all of its old enemies such as predators and parasites.
The European winter temperatures are much colder than those experienced in Australia. Only European wasp queens survive the European winter, meaning that each year, the wasp nest begins with a single individual. In Australia, the temperatures are such that the worker European wasps can survive the winter. This means that if a new queens remains in her old nest, the nest does not begin with a single individual, but with a new queen and several thousand workers. These nests are called 'overwintering' nests and by summer may have increased in size to house over 100,000 worker wasps.
Associated Health Problems
A European wasp nest commonly contains from several thousand to tens of thousands of individual wasps. If their nest is disturbed, European wasps are more aggressive than native wasps in protecting the nest.
The sting of the European wasp does not contain barbs like those found on the sting of a honey bee, therefore the wasp can sting a victim repeatedly. When a bee stings a victim, the barbs on the sting keep the sting in the victim.
The wasp is also able to release an alarm pheromone (or chemical signal) that 'marks' animals which disturb their nest, attracting other wasps to the sting site.
The venom from the sting of a European wasp contains several toxins, which may cause a hypersensitive or allergic reactions in some people. Studies have shown that about 10% of people stung more than once become allergic to wasp venom.
The greatest health risk posed by European wasps is if stung in the mouth or back of the throat. The soft tissue in these areas will immediately swell and may cause breathing difficulties. For this reason, we recommend that you NEVER drink directly from a can or bottle outdoors.