‘Bug boom’ as warmer weather increases cockroach and ant populations

Shane Warland of Debug Nelson is struggling to keep up with demand.

“Everything is booming,” Warland said. With “everything” he refers to cockroaches, ants, rodents and wasps.

The number of calls has increased noticeably over the past three years, Warland said.

New Zealand has about 40 species of ants, 12 of which are native. Of the 30 species of cockroaches that live here, about half are native.

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In Nelson, the main invaders were Argentine ants, white-footed house ants and German cockroaches, Warland said.

People often saw Gisborne cockroaches (native to Australia), he said. “He comes in when a window or door is open. People see them and think they have a plague.”

However, this species tended to live outdoors, eating rotten vegetation and only going indoors when it was cold.

It was German cockroaches that can really take hold, Warland said.

“There was a lady who picked up a coffee maker from a store that was infested with cockroaches. Once they spread, they got everywhere, they breed so fast.”

They will also settle behind dishwashers and refrigerators, in microwave motors and behind electrical outlets.

The Gisborne cockroach, native to Australia, usually lives under the mulch in your yard and feeds on vegetation.


The Gisborne cockroach, native to Australia, usually lives under the mulch in your yard and feeds on vegetation.

“Where it’s warm and cozy and dark and nobody bothers them,” Warland said.

Keeping a clean house helps deter these bugs, but he’s also seen tidy homes infested.

‘I’ve seen clean houses where ants come in because they’re passing through. You can be clean, but once you have white-footed house ants, they get into your walls and ceilings.”

The best solution for many people was to attack ants with fly spray or insect bombs. But this could make a problem worse, Warland said.

“They’ll think they’re being attacked, so they split their nest and breed like crazy.”

This will often be in hard-to-reach places: interior walls or ceilings.

Martin De Ruyter/Stuff

“Once [German cockroaches] they were scattered everywhere, they breed so quickly,” says Shane Warland.

Because the queen only consumes food produced in the nest, ingesting bait may also be ineffective, Warland said.

The best way to deal with ants was to use a non-repellent insecticide, which ants, which “feeling sensitive,” were transferred to the nest through their bodies, he said.

The unwanted invaders were getting more and more resistance, Warland believed.

‘They get used to what we serve them. They are survivors; they’ve been around for a long time, they’ve walked with the dinosaurs.”

Entomologist and science communicator Morgane Merien said the invaders at home are usually the introduced species.

The Argentine ant is one of the most spotted insects in people's homes.


The Argentine ant is one of the most spotted insects in people’s homes.

“The native species mostly stay in their native habitats and are quite harmless and even beneficial to some of the services they provide to our ecosystems.

“I think more people are seeing these introduced ants and cockroaches because our summers are getting longer and warmer, leading to greater numbers and a longer breeding season,” Merien said.

Merien, who presents TVNZ’s Bug Hunter, said cold weather forces insects to seek warmth and shelter. And because we’re more indoors for the same reason, we’re more likely to run into them, she said.

As the climate warms, introduced insects that previously wouldn’t have survived in New Zealand are likely to start to thrive, she said.

Some (such as the brown-marbled stink bug, the spotted lanternfly and the gypsy moth) can cause problems in the agricultural sector.

“It’s important to keep an eye out and report any strange looking critters you don’t know about to the Ministry of Primary Industries.”

Ruud Kleinpaste, known to television viewers as the Bugman, doesn’t like the word ‘pest’ and makes sure he doesn’t use it when he lectures to children.

‘Do you mean an unwanted insect? What is the unwanted part of it? The only pests are the ones that don’t belong here in our ecosystem and are altering our natural habitat.”

Cockroaches are useful creatures: The Gisborne variety breaks down the vegetation under the mulch in your yard, while German cockroaches are the “world’s best recyclers,” naturally collaborating with the messiest animal on Earth: humans.

The Bugman, Ruud Kleinpaste, does not like the word 'pest'.  'Do you mean an unwanted insect?  What's the unwanted thing about it?”


The Bugman, Ruud Kleinpaste, does not like the word ‘pest’. ‘Do you mean an unwanted insect? What’s the unwanted thing about it?”

“If you get cockroaches, ask about your own hygiene systems at home,” Kleinpaste said.

“If you spill spaghetti bolognaise at home, they’ll come in and leave a business card and say, ‘Don’t worry, I’ll clean it up, I’ve been doing this for five million years’.”

Kleinpaste is more concerned with the insects that damage our crops: like guava moths that migrate south, and other creatures that wouldn’t have survived if our climate were cooler.

“Those are pests, from a biosecurity standpoint.”

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