Could wasp hunting save endangered coastal moths?

Invasive predators have moved in on a coastal stretch of the South Island where rare native species are easy prey.

But new research is hoped to shed light on whether the public could help to put a dent in the European and Asian paper wasp populations.

“They’re basically the stoats of the insect world,” Marlborough-based researcher Simon Litchwark said.

Litchwark was part of a team led by the Department of Conservation (DOC), conducting research in Cloudy Bay by removing paper wasp nests and analysing the results.

The area was home to some “really special stuff”, such as the rare native Kiwaia, or Cloudy Bay moth, which was previously feared to have become extinct, until four small populations were found in Marlborough in 2021.

Litchwark said he had noticed a decline in certain insect species along the bay’s coastline, though it was difficult to say whether paper wasps could be directly

blamed. “There’s definitely been changes in the moth communities out there, so [we’re] just trying to tease out what’s causing that,” Litchwark said.

But the predators were not fussy eaters, feeding on “everything in sight,” including the caterpillars of flying insects.

Unlike other species in their order, the European and Asian paper wasps did not take kindly to baits, so tools to control their numbers were limited, he said.

So the research team was looking at the effectiveness of eliminating their nests by hand, and whether it was worth empowering the public to do the same.

DOC science advisor and research lead Eric Edwards said killing a nest was a simple process. “If there’s any wasps sitting on the nest, then they’re wasps that are able to build a new nest, so if you have a can of fly spray, you can just give it a little zap,” he said.

Nests were attached to vegetation which on a beach rarely grew above waist height, meaning paper wasps were easier to target on the coast than in other environments, he said.

The nests, looking like “pebbles made of paper” in spring when they were first becoming established, Edwards said, sometimes grew to the size of a tennis ball later in summer.

Picking off the nests after spraying was all that was required to kill the larvae and eggs inside, which he said could not survive on the ground.

“I mean that’s the beauty of it right, it’s not a tricky technology, it’s low-tech.”

ROBERT HOARE The Kiwaia or Cloudy Bay moth was previously thought to have become extinct. Also known as a mat daisy jumper, it is flightless and jumps to get around.

SIMON LITCHWARK European and Asian paper wasp nests in the Cloudy Bay area often grow to the size of a tennis ball.