Why are European Wasps pests in Australia?

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 barbecues and interfere with outdoor activities. School bins in the playground are often abuzz with European Wasps searching for and feeding on food scraps and entering drink cans.

European Wasp on a drinking straw

European Wasp on a drinking straw
Photographer: Otto Rogge. Source: Otto Rogge Photography

Wasps can sometimes be beneficial by removing caterpillars and other such garden pests. However, they make pests of themselves by damaging ripening fruit. To help reduce the number of European Wasps, the home gardener should continually clear all fruit that has fallen to the ground. European Wasps can cause economic loss and problems during fruit-picking in commercial orchards. In New Zealand they have caused considerable losses to the honey industry, but similar losses have not been recorded in Australia.

Adult European Wasps

Adult European Wasps
Photographer: Otto Rogge. Source: Otto Rogge Photography

Factories and shops processing or selling fruit, cakes or soft drinks often have problems with wasps attracted to the smells. The problems occur either when these wasps annoy the workers, or when they are accidentally incorporated in and contaminate food products.

The problems caused by European Wasps are greater in newly invaded places, such as Australia, than they are in their native home of Europe. There are two main reasons for this:

  1. When the wasp invades new countries, it leaves behind all of its old enemies such as predators and parasites;
  2. 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 also survive the winter. This means that if a new queen 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 over-wintering nests and by summer can increased in size to house more than 100 000 worker wasps.

What health problems can European Wasps cause?

European Wasp nests can contain between several thousand and tens of thousands of individual wasps. If the nest is disturbed, European Wasps are very aggressive when protecting the nest; far more so than native wasps. The sting of the European Wasp does not contain barbs like those found on the sting of a Honey Bee, so a wasp can sting a victim repeatedly; when a bee stings a victim, the barbs on the sting keep the sting in the victim.

Wasps are also able to release an alarm pheromone (or chemical signal) that ‘marks’ animals that disturb their nest, attracting other wasps to the sting site.

A European Wasp in a drink bottle

A European Wasp in a drink bottle
Photographer: Otto Rogge. Source: Otto Rogge Photography

The venom from the sting of a European Wasp contains several toxins, which may cause 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 a person is 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 you should NEVER drink directly from a can or bottle outdoors.

First aid for European Wasp stings

The sting from a European Wasp is more painful than the sting from a Honey Bee. For most people, a painful reminder of the sting, sometimes lasting several days, is the only after-effect they will suffer.

Applying an ice-pack to the sting site helps reduce the pain and swelling. The ice-pack should contain a mixture of ice and water; do not place ice directly on the skin. Some sting victims may have a hypersensitive reaction, while others who have suffered several stings, may develop an allergic reaction. Allergic reactions to a sting may involve puffiness of the skin extending well beyond the sting site, or the development of an asthma-like condition that makes breathing difficult; in severe cases the heart may stop beating. If a victim is suffering breathing difficulties, then a salbutamol inhaler (e.g. ‘Ventolin’) should help breathing.

When a known wasp-allergic person is stung on a limb, the recommended first-aid treatment is the same as for snake bite: the pressure–immobilisation technique. The limb is kept still while a bandage is wound firmly around the sting site. Wrap the bandage around the limb a few times away from the heart side of the sting (i.e. towards the fingers or toes), then firmly wrap as much of the limb as possible, bandaging upwards to the groin or shoulder. The wrapping pressure should be firm but not constrictive. Seek medical attention as soon as possible. NEVER APPLY A TOURNIQUET.

Comments (2)

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shayne worrall 22 May, 2009 11:06
I know there are European Wasp near to the property i live.How do i get rid of them, because i have fruit trees.
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Discovery Centre 24 May, 2009 14:51

Hi Shayne,

Unfortunately, it is not part of the Museum's service to offer pest eradication advice - the best thing for you to do would be to contact a couple of pest control companies and go with the one you think is best.

The Museum can offer an identification service if necessary - feel free to lodge an identification enquiry here.

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