Pest controllers warn of insect invasion after warm wet weather

An expert warns mosquitoes are going to be particularly bad.
An expert warns mosquitoes are going to be particularly bad. Photo credit: Getty Images

By Jean Edwards of RNZ

Get ready to be bugged by flies this summer - pest controllers warn the warm, damp weather in many parts of the country is going to bring crazy numbers of insects over the next month.

A perfect storm of drenching rain and seasonal sultriness is tipped to provide ideal breeding conditions for a proliferation of flies, mosquitoes and other bugs like ants.

Pest Management Association of New Zealand vice president Dr Paul Craddock said flies were climate-driven creatures with a life cycle of about a week.

"My prediction would be, the fly season is going to go pretty crazy. We're going to see a lot of flies around, and also mosquitoes and other general insect activity like ants.

"There's going to be a lot of standing water around in drains and places like that, so mosquitoes are going to be particularly bad."

While it was hard to predict exactly how bad the season would be because of localised conditions, Craddock - an entomologist - said people should expect many more flies buzzing around their house.

"Generally speaking, it's going to be worse than usual."

Houseflies, blowflies, mosquitoes, fruit flies and midges were all expected to multiply in January and February, along with ants, which were anecdotally on the march in Nelson.

Debug Nelson owner Shane Warland said a mild winter had failed to kill bugs off, paving the way for an influx of flies and ants once the rain cleared.

"I think this summer is really going to boom for ants," he said.

"A little bit of rain and they head for high ground, so inside they come. A lot of them know before the weatherman does - you'll see them on the move."

Piles of grass clippings were the perfect incubator for flies, Warland said.

"I think we're going to have a major influx of flies. The last couple of years haven't been too bad, but this season I think they're really going to bounce, they're going to take off."

While flies were primarily a nuisance, Craddock said people should stop them crawling over food.

"There's strong evidence to show that they will spread food-borne illnesses. Essentially, they're carrying the bacteria on their bodies and they're jumping from the dog faeces in the backyard onto your BBQ salad and sausages."

Attracted by the smell of food, cooking, rubbish and pets, Craddock said good airflow was key to keeping flies out of the house.

"Although it's in the name, flies don't really like it when it's windy - they prefer still air, because they kind of get blasted around."

Ceiling or pedestal fans and flyscreens worked well, along with good household hygiene like cleaning kitchen benches, disposing of smelly rubbish, keeping pet bowls clean and picking up dog poo, Craddock said.

Warland treats the inside of homes for flies with a spray that leaves a residue on window sills and flat surfaces like kitchen ceilings.

"The fly lands on it, and the first thing a fly does is put his feet in his mouth - a bit like a politician - and picks up the poison that way," he said.

Another reason to resist climate change

Craddock said climate change-driven changes in weather patterns could influence the fly season.

"That means the fly season is potentially longer, or we're seeing problems in places people haven't had problems before - places in the deep south of New Zealand like Bluff or Invercargill."

Despite New Zealanders' almost universal hatred of flies, Craddock said the insects were simple creatures devoted to feeding and breeding.

"They are just like any other biological organism trying to make their way in the world. There's nothing particularly malicious in what they're doing, they're just trying to take advantage of their environment.

"They're a fascinating creature. They've evolved over many millions of years to do what they do, and they do it very, very well."