Voracious killer wasps are causing some of New Zealand's native bugs to go extinct, insect experts believe.
Wasps are a serious problem for people on picnics, but their effects on native insect populations are devastating.
The lifespan of native insects in wasp-dense areas can be a matter of hours, and native species may even have been driven extinct.
Victoria University insect ecologist Professor Phil Lester says he was "sure" there have been local extinctions.
"There must have been at least local extinctions of species, things like the forest ringlet butterfly that we just don't see many of anymore," he says.
The more wasps, the worse the effects they have on the ecosystem, and Lester says this year is looking like it's going to be a "bumper year for wasps," thanks to the hot, dry spring.
Last year, The Nelson Mail and Stuff launched a community campaign to wipe out wasps.
With help from the Department of Conservation (DOC), the community, and other conservation groups, the Wasp Wipeout campaign raised over $50,000 and saw a 98 percent reduction in wasp populations.
Hundreds of volunteers set Vespex bait traps along hundreds of kilometers of DOC walking tracks and public areas, and this year the program is expanding into a nationwide effort.
Wasps have a very high requirement for protein in their diet, and their primary source is other insects.
University of Auckland Associate Professor Jacqueline Beggs ran a study to determine the effects that wasps have on their fellow invertebrates by placing lab-reared spiders and caterpillars into wasp-dense areas and timing how long they lasted before wasps found them.
"In some cases, you barely put the jolly thing on the plant and whoosh - it was gone," she says.
Beggs found the majority of the prey insects were gone within the first half hour, and from her data calculated that the chances of those insects surviving to reproduce in high wasp years were "next to zero".
Some of the flow-on effects of this are obvious, and still more effects are happening on a scale that most people won't notice.
Birds are not only out-competed for the honeydew wasps greedily guzzle down, they are also out-competed for the insects they might snack on.
Lester says many people told him about the changes in birds' habits depending on the number of wasps.
"People in Lake Rotoiti that supplementary-feed birds with sugar-water tell me when there's a high number of wasps the birds are hungry, but when people come and use Vespex you don't see nearly as many birds at the supplementary feeders," he says.
Wasps are generalized and opportunistic feeders. They don't target any particular insects - rather, they eat them all, starting with the big ones and working their way down when they run out.
"Particularly for the larger-bodied insects, for giant dragonflies, stick-insects, and weta, those things are just absolutely hammered by wasps," Beggs says.
"Then they just start eating smaller and smaller things, so by the end of a high-density wasp season, I've seen them eating little sandflies off the windows of huts. They're scraping the bottom of the barrel, and your heart just sinks, you think 'oh no, that just means they've eaten everything else'."
While there is no documentation to show that wasps have been directly responsible for local extinctions, Beggs says regardless, the damage they do to ecosystems should not be underestimated.
"Wasps really do restructure the whole community, I mean extinction is awful because it's forever, but even just shifting the relative abundance of things, we end up with systems that are just completely dominated by these introduced species," she says.
The danger there is that an imbalance in the invertebrate world can lead to unknown knock-on effects.
"Insects drive the food-chain, birds and other insects and lizards will feed on them. They're doing the creation of soil, they're often driving pollination, and nutrient turnover, just so many things. Insects are the real drivers of ecosystem functioning, so the fact that that is being impacted, as an ecologist, leaves me really worried."
Those ecological effects have already been playing out for decades, as common wasps have been a major problem since the seventies, and German wasps since the 1940s. But so little is known about the insect world, it is unclear what those effects are.
Bugman Ruud Kleinpaste, who has dedicated much of his life to insects, says bugs "fly under the radar".
"We actually know very little about insects full stop. We don't even know how many species there are, we know of about a million, there might be 12 million, 15 million, we don't know. But even more than that we don't know what their ecological niches are."
But enough research has been done to show "the overall effects wasps have on the invertebrate world is just devastating".
Those effects aren't limited to native insects, either.
Honey-bees are a target of wasps, and this along with their other effects lead to wasps being calculated as a $133 million drain on the economy each year.
So wasps are costing us a healthy ecosystem, our unique biodiversity, and hundreds of millions of dollars in lost productivity. But we can fight back.
"Vespex is a revolutionary tool," Lester says.
"The formulation that's been developed is one that's very attractive to wasps, it's a protein matrix that's really appealing to wasps and not other insects like bees. And when it's nailed to a tree and only left out for a few days, that limits its non-target effects."
Last year's Wasp Wipeout lead to 98 percent reductions in wasp numbers wherever the bait was used. In some cases, the effects were immediately noticeable.
Nik Joice says it could take as little as a single day to see improvements after a Vespex
"In a really high wasp year, you put the bait out and the next day you can hear birdsong again."
Not every recovery will be so quick.
Beggs estimated even after a total eradication of wasps, it could still take years for insects with low reproductive rates to recover.
Kleinpaste says that since we don't know the full effects that the wasps are having, "it will pay for us, all New Zealanders, to look after biosecurity and become nature-literate, and look after the environment".
