Charles McClintock from Sumitomo Chemical Australia examines the various methods of controlling wasps, including the dangerous European wasp.
Any wasp nest can be a serious worry for a homeowner and a European wasp nest can even be a serious worry for a pest manager! With wasp season approaching, it is worth reviewing the various techniques used to deal with these dangerous insects. Certainly the products and application techniques utilised will depend on the wasp species and nest location.
The Asian paper wasp and various native paper wasps are found across Australia. Although the different species vary in their level of aggression, they are generally not considered dangerous unless disturbed. With exposed nests and colony sizes of generally less than 200 individuals, the treatment of paper wasps is relatively straightforward.
The open structure of paper wasps’ nests allows for easy direct nest treatment. A specialised wasp aerosol such as WaspJet from Sumitomo provides an ideal option. With a spray range of up to six metres and delivering an output of over ten grams per second, it can immobilise and kill the wasps immediately without getting too close to the nest. With its low conductivity formulation, it can be safely used around electrical areas, where wasps may often build their nests.
Preventing paper wasps from building their nests on buildings in the first place is also straightforward. A general pest treatment covering the eaves of the house in early spring will also prevent wasps from building their nests. Pyrethroid products, having contact repellency properties, are often a good choice, with Sumiguard being a broad-spectrum, cost-effective option.
Dealing with European wasps is a whole different ball game. European wasps are generally found in the southern states from Sydney down to Tasmania and across to Adelaide. In Perth they are a reportable pest and although there has been the occasional nest found in southeast Queensland and climate modelling suggests they could survive in Queensland, they have yet to become established in these subtropical areas.
European wasps are a more aggressive wasp species, coupled with their large nest size – normally the size of a soccer ball with around 3000 individuals, but can reach 10,000 or more – they are certainly a danger to those living nearby. The other challenge with European wasps, that makes them more difficult to control, is their preferred nesting locations. Around 80% of nests will be hollowed out holes in the ground, with around 10% being in various low lying but above ground locations, with the remaining 10% being arboreal, in trees, on buildings or in roof voids/wall cavities.
Small above-ground nests can be dealt with using a specialist Wasp aerosol such as Waspjet, as their nest structure is open. As the nest grows, in exposed situations the wasps enclose the nest with a protective covering, normally leaving only a single opening for the wasps to fly in and out. Successfully treating such nests involves not only coating the outside of the nest, but making sure insecticide gets inside the nest. Applying a spray, dust or aerosol through the nest entrance is required.
When treating nests in wall voids, dusts or an aerosol such as Sumiblast are often the better options, as they fill the void with insecticide. Similarly, when treating nests in the ground, blowing dust into the nest (using an extension of plastic tubing if you’re nervous!) is the preferred option. When applying such products, they should be applied to excess to ensure a thorough treatment and no escapees.
Safety is key. In treating European wasp nests, ensure you wear a full bee suit with headgear. Ideally, treat the nest in the evening, when the wasps are all back in the nest and more docile. If lighting is required, use a red filter (as insects cannot see red light). Of course make sure all other people and pets are kept well clear.
Charles McClintock, Professional Products Business Manager, Sumitomo Chemical Australia