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Keen Mahurangi West gardener Isabel Harris is sounding a warning about the autumnal activity of the Asian and Australian paper wasp.
Introduced wasps are a significant pest, which harm native birds and insects, and are a threat to human health and recreation.
“At this time of year they are busy developing young that will soon hatch,” says Harris. “The paper wasps are black with yellow stripes, smaller than the German wasps that nest in the ground and in buildings.”
“They have steadily increased in number over the years to become almost in plague proportions in some areas.”
The paper wasp makes its honeycomb shaped nests out of regurgitated woody material. The adult wasps can be seen on wooden railings, fences and even decks and outdoor table settings, where they chew the wood to make a pulp to build their nest. The nests themselves can be found attached to railings or shrubs, often tucked in amongst agapanthus leaves.
Harris says these wasps deliver a nasty sting if you inadvertently disturb a nest while gardening.
“They compete with our honey bees for nectar and eat caterpillars, particularly those of the monarch butterfly.
“You can help slow the spread of these wasps if you keep your eye out for their nests, which will be constantly attended with wasps coming and going during the day, then settled on in the later evening.”
While Harris says she uses fly spray to kill the wasps, the Department of Conservation recommends using Vespex if controlling wasps over a large area. Vespex is a protein (meat-based) bait, containing the insecticide fipronil, which is deployed from a bait station. Wasps take the bait back to their nests to feed their young, wiping out the nest.
The bait is targeted at wasps and is not attractive to bees, but it is only effective at certain times of the year when wasps are eating protein. In order to purchase Vespex, you need to be registered with manufacturer Nelson-based manufactuer Merchento as an approved user.
“The bees and butterflies will be thankful for your efforts,” Harris says.
Additional information, from Ken Brown, Auckland Beekeepers Club vice president
I am unaware of any bait that paper wasps will take back to their nest, thereby poisoning the brood and destroying the colony. However, there are two methods that work well:
The most effective method is to spray the nest in the evening with fly spray. Their nests are easy to see (German and common wasps tend to live in burrows in the ground or in cavities). Spray in the evening when they’re all at home.
The other method is to use a trap with an attractive lure. Traps and lures are commercially available in hardware and gardening stores. Or you can easily make your own.
Cut a plastic soft drink bottle 2/3 the way up and put the top part upside down into the bottom part thus creating a funnel for the wasp to go down into. Inside the trap put sugar water and vinegar (to discourage bees) to attract them in spring. In late winter and autumn, when they’re in their protein stage, use tuna, chicken, ham or any meat.
Of note is that wasps are an essential part of our ecosystem, killing many pests. Paper wasps don’t kill bees and they don’t tend to sting humans unless provoked. Their stings are very painful though, much more so than bees.
