Wasp wipeout takes flight
Wasp Wipeout is back and bigger than ever.
The third annual effort to keep New Zealand’s summers wasp-free will be covering not only te tau ihu (the top of the South Island) but also Canterbury and the West Coast.
In previous years, Wasp Wipeout has been up to 98 per cent effective at reducing wasp populations in Nelson, Marlborough, and the Tasman district.
That success has seen the wipeout programme take flight and spread into previously uncharted areas.
The Wasp Wipeout programme is aimed 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 1900s when they first established themselves here. German wasps have been in
New Zealand since 1945, and common wasps since the 1970s.
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 programme. They are some of many native insect species which will benefit from the removal of the invasive species which are now New Zealand’s most dangerous predators.
It may seem an exaggeration but New Zealand doesn’t have many predators. Wasps collectively account for a huge amount of damage to the economy, estimated to cost $130 million per year; the environment, potentially causing localised insect extinctions and stripping forests of resources native animals rely on; and to people, causing anything from painful stings right up to hospital visits and anaphylactic shock. New Zealand, and the Nelson Lakes district 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 around 40 billion wasp queens and many tens of thousands more worker wasps roaming the woods.
In spring and early summer, German and common wasps building their nests eat exclusively carbohydrate, or sugar, stripping the forest of honeydew in particular, an important part of the diet of many native birds such as tui. After stripping the forest of vital food resources, in midto-late summer the wasps swap to a protein-based diet, exterminating insects with ruthless efficiency.
Wasps collect protein in the form of insects, road-kill, and anything else they can find and bring it back to their nest to feed their larvae.
This is the stage of the wasp lifecycle that the wipeout programme targets, using Vespex bait. Vespex is a protein-based bait which is not attractive to bees but deadly to wasps while being relatively non-toxic to humans or pets.
The active ingredient in Vespex is Fiprinol, a common insecticide, found in everything from flea-powders to ant poisons. It takes only one wasp taking a tiny portion of the bait back to its nest for it to effectively wipe out the nest, as social wasps share the food around to all larvae.
Targeting the larvae also hits the worker wasps, because, at this stage of the life-cycle of a wasp nest, workers eat only food which has been pre-digested by the larvae.
The poison is targeted at wasps through 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 removed to limit the amount of bait taken by non-target insects.