Trout flies invade Rotorua lakeside

By MIKE MATHER in Rotorua
To some they are simply a natural part of living in Rotorua. For others, they are a pestilence that must be wiped off the face of the Earth.

The trout flies - or naho naho - are out in force and flying in the face of all who live or venture near the lake.

The flies have become the bane of people involved in outdoor activities at dusk. Those barbecuing food often find themselves with the tiny flies stuck to their steak and sausages. Cyclists going for an evening ride dare not open their mouths, lest they find themselves swallowing an unexpected meal of naho naho.

One lakeside resident, Valerie Atkinson, said she was fed up with the "little beasties".

"They drive me mad. You can't sit still or else they come along and land on you. You can't have the windows open or else they fly in for a visit.

"Even if you turn off the light they still decide to fly in front of the TV and do their dance on the screen."

Every morning Mrs Atkinson faces cleaning up trout fly corpses from the toilet or other rooms where a light had been left on at night.

"There's always a nice big pile of them. They manage to get everywhere, even up my dog's nose when I take him for a walk."

But while many were frustrated by the prevalence of the insects, Rotorua District Council regulatory services manager Jim Nicklin said the trout flies - actually the larvae of bloodworm, which hatch from sediments in the lakebed - were a natural phenomena in Rotorua and pre-dated human settlement.

"They are nothing new in Rotorua.

"This issue last reared its head in 1999 in the form of a submission to the [council's] annual plan.

"In response, some research was made and a pamphlet was produced and distributed to every home in Rotorua."

The insects have a 12-hour lifespan and swarm in a frenzied attempt to mate and reproduce before time runs out. As many as 500,000 can be found in a square metre.

This year's apparent increase was due to the warmer weather, combined with the invasion of the naho naho's habitat by humans, who had been clearing wetland areas for subdivisions and building developments.

There was no known effective repellent for them and trying to kill them with flyspray was a hopeless battle, "like trying to hold back the tide", Mr Nicklin said.