Very high wasp numbers indicate a nest or nests within several hundred metres. Efforts should be made to locate these nests and destroy them, as large numbers of wasps have a great effect on hives in an apiary.
Flying wasps can be tracked early morning or at dusk when other insects such as bees and flies are not flying. Wasps can be dusted with flour or icing sugar to make them more conspicuous.
Wasps can be dangerous so take the following precautions:
- Carry out work in the evening, after the wasps have ceased flying.
- Wear gloves and a veil, if available.
Nests in the Ground
Flying wasps entering and leaving a small hole in the ground usually indicates that an underground nest lies beneath. There are various ways to exterminating ground nests, the more successful of which are;
- Dust insecticide around and into the entrance of the nest, when all of the wasps have returned for the night. Use about 50g (about 2 tablespoons) or more of the insecticide powder, and do not plug the hole.
- It may take a few days to kill all the wasps, as young wasps will continue to emerge from the brood combs. It may be necessary to repeat the operation after about 7 days. When all adult wasps have died, the hole should be blocked to prevent newly hatched wasps from emerging.
- Always follow the instructions, all modern insecticides demand respect for their toxic properties when being handled.
Nests in Roofs and Basements
A method of wiping out a nest in the roof or basement is;
Use a "borer bomb". Simply place the "bomb" in a tin (to reduce fire risk), place near the nests in the evening and ignite. Notify the fire brigade to prevent false alarms.
Nests in Walls
If the wasps are entering a wall through a small hole, the following methods can be used to destroy the nest;
Cut off about 100mm of a hose which can fit in the hole. Pack powdered insecticide into it and tap the hose until the powder has compacted to one side. Place the hose in the hole. Wasps must then walk over the insecticide to gain access to their nests. All other possible entrances must be blocked.
Blow the insecticide in; pack one end of a suitable length of garden hose with about 50g (2 tablespoons) of insecticide. Place the end with the powder in the entrance of the nest, the other end in the mouth and then blow sharply.
Nests in the Open
In the evening, thoroughly soak nests with concentrated insecticide solutions, or place powdered insecticide around next entrance. After the wasps are dead, move the nest to a safe place and burn it.
Unfortunately, Council no longer offers a wasp eradication service, although there are various companies around the district that offer wasp extermination services, please refer to the Yellow Pages for more information.
If you come across wasps on Council land, please call the Clutha District Council office on 03 419 0200 and we can arrange disposal.