Wasps
The most common wasp in New Zealand is the German Wasp, introduced in 1922 and now widely distributed. For most of the year it is an ally, not a pest, as it eats other insects while raising young in the nest. It only becomes a nuisance in late summer and autumn.
Wasp nests, made of chewed up wood pulp, are usually found in the ground, in trees, under houses or in roof spaces. They can range from the size of a golf ball to huge nests some 2m across. In most cases, particularly in Dunedin, the wasps die off over winter, with the exception of the queen who hibernates to continue breeding the following season.
Finding the nest
If the wasps have become a real nuisance, you will need to find and destroy the nest. Do this by watching the wasps. Look out for areas where a lot of wasps are milling around buildings, vegetation or sloped ground. Do not approach the nest site during the day without protective clothing, as you may be seriously injured.
It is best to destroy a nest at dusk, after the worker wasps return to the nest. As night falls, they become sluggish and less aggressive, reducing the danger. If you look carefully, you may find small entrance holes roughly 3-5cm across.
Destroying the nest
When you have found it, apply a suitable insecticide such as Carbaryl or Yates Wasp Dust directly to the nest. These and other powdered insecticides are available at any hardware or garden store. If you are allergic to wasp stings, we suggest you consult a professional exterminator, as the wasps may react.
Apply 2-3 tablespoons of the insecticide to the point where the wasps land prior to crawling into the nest. They eat the powder as they try to remove it from the nest entrance and die within a very short time. You may need to apply a second dose several nights later if you have not had a total kill.
If you can’t reach the nest, try poisoned bait, such as processed fish or cat food, laced with insecticide. This may not destroy the entire nest but it can effectively reduce the wasp numbers. It is a good idea to hang the bait in a mesh bag from a tree or roof, as it will appeal to other animals including pets.
It is not a good idea to use petrol or kerosene to fumigate nests. As well as being a potential fire hazard, the wasps can react violently to the fumes, attacking in great numbers and with ferocity.
Swarming bees
If you have a problem with swarming bees, contact the Otago branch of the National Beekeepers Association. They will give you contact information for a local beekeeper who will remove the bees for you.
Last reviewed: 19 Mar 2009 12:36pm
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