Wipeout spreads its wings
Top of the south’s successful summer wasp blitz is expanding
It’s that time of year again, and Wasp Wipeout is back – and bigger than ever.
The third annual effort to keep New Zealand’s summers waspfree will be covering not only Te Tau Ihu (the top of the South Island), but Canterbury and the West Coast as well.
In previous years, Wasp Wipeout has been up to 98 per cent effective at reducing wasp populations in Nelson city, Marlborough and Tasman district.
The success of previous years has seen the programme take flight and spread into areas where wasps have until now run rampant and unchecked.
The programme is taking aim at common and German wasps, two invasive wasp species which have no predators in New Zealand and have had the run of the country since the mid-20th century, when they became established here.
German wasps have been here since 1945, and common wasps since the 1970s.
It is believed German wasps were accidentally introduced in cargo, and there were up to 10 different accidental common wasp introductions.
Unlike the invasive species, New Zealand’s native wasp species tend to be small, solitary, and quite rare. These wasps are not a target of the Wasp Wipeout programme, but are some of many native insect species which will benefit from the removal of the invasive wasps, which are now New Zealand’s most dangerous predators.
Wasps account for a huge amount of damage to the economy, estimated at $130 million a year; the environment, potentially causing localised insect extinctions and stripping forests of resources native species rely on; and to people, causing anything from painful stings to hospital visits and anaphylactic shock.
New Zealand, and the Nelson Lakes area in particular, have some of the highest densities of wasps in the world.
At the height of summer there can be up to 40 nests per hectare of beech forest; that’s somewhere in the realm of 40 billion wasp queens and many tens of thousands more worker wasps roaming the woods.
The life cycle of these social wasps means they are devastating to almost every New Zealand native species.
In spring and early summer, German and common wasps building up their nests eat exclusively carbohydrate, or sugar, stripping the beech forest of honeydew in particular, an
important part of the diet of many native birds like tui.
After stripping the forest of vital food resources, in mid- to late summer the wasps swap to a protein-based diet, exterminating insects with ruthless efficiency.
Wasps collect protein in the form of insects, roadkill and anything else they can find, and bring it back to their nest to feed their larvae.
This is the stage of the wasp life cycle that the Wasp Wipeout programme targets, using Vespex bait.
Vespex is a protein-based bait which is not attractive to bees, and which is deadly to wasps while being relatively non-toxic to humans or pets (though people are still advised to handle it with care and make sure to keep it out of reach of children).
Vespex is extremely effective, with the active ingredient, fiprinol, doing all the heavy lifting. Fiprinol is a very common insecticide, found in everything from flea powders to ant poisons.
It only takes one wasp taking a tiny portion of the Vespex bait back to its nest for it to effectively wipe the nest out, as social wasps share the food around to all their larvae.
Targeting the larvae also hits the worker wasps, because at this stage of the life cycle of a wasp nest, workers only eat food which has been pre-digested by the larvae.
The poison is targeted at wasps thanks to the formulation and placement of the bait. Bait stations are nailed to trees, easily accessed by air but a little bit tougher for crawling bugs to find.
The Vespex is put out for a limited time, just one week, and then any remaining bait is taken out of the environment again, to limit the amount of bait taken by non-target insects.