Sunday, December 5, 2010

Insect Stings

We have few stinging insects in New Zealand but the few we have can cause more than just a nuisance; they can be a threat to our health.

Wasp Sting
Wasps and honey bees possess stings they use to protect themselves and their colonies. The hypodermic sting is inserted through our skin and venom is injected. Pheromone chemical signals are released when a bee or wasp stings. The pheromone induces other bees or wasps to also sting. So if you are stung once it is good advice to ‘calmly’ move away from any other wasps or bees.

The venom in a single sting will always cause pain but it can also cause life threatening anaphylactic shock in sensitive individuals. If they are aware of their hypersensitivity to stings such people will carry a supply of adrenalin for rapid administration. Adrenalin can save the life of someone suffering anaphylaxis.

Those that are not hypersensitive to stings can still be threatened by bees and wasps. Honey bees can form colonies of up to 50,000 individuals and Common and German wasps may have several thousand in a nest. These very large numbers can make them a very real threat to life if they are disturbed. More than 10 stings can cause serious swelling in most individuals. Medical attention should always be sought if sting sites are near airways where swelling might impede breathing.

Bees and wasps only sting when they or their colonies are threatened. Unfortunately we can induce stinging accidentally, such as in cases of sitting on a bee in the garden or disturbing a wasp nest that has been formed in a compost heap.

Honey bees are regarded as beneficial insects, not just because of their honey production but because they pollinate many of our crops. Only if a honey bee nest is built in the ‘wrong’ place should it be moved or destroyed. If you have a swarm or nest in a bush in the garden your local beekeeper will often come and collect it at no cost. If the nest is in the eaves of a house or other inaccessible place they can be destroyed, but any honey store must also be removed or new colonies are likely to move in to take over the nest.

On the other hand German and common wasps are invasive pests and can be build up to large densities, particularly in New Zealand’s native beech forests where they feed on the honey dew extruded by scale insects. They are a threat to New Zealand’s biodiversity. Wasp nests can easily be destroyed with Kiwicare NO Wasps carbaryl wasp dust puffed into the entrance of the nest.

As well as wasps and bees there are ants that bite and then spray the bite wound with venom. There are not any such ants in New Zealand but there is a real risk that biting ants such as Red Fire Ants or Crazy Ants could be brought in to the country and become established. The sting of Fire Ants is painful to both humans and animals. There have been three incursions of Fire Ants in New Zealand since 2001 but these have been successfully eradicated by MAF Biosecurity. If you want help prevent invasive organisms damaging New Zealand’s environment join the NZ Biosecurity Institute. A very modest $30 per year.

The Kiwicare website and help desks are often contacted for advice on identification of insects and how to deal with nests and prevent stings.

Did you hear about the dyslexic wasp?
It has six paws and zubz around all day.

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