Cockroach boom sends bug business soaring

The Gisborne cockroach is easily identifiable because of the white stripe which runs along its sides. Photo / Supplied

Aucklanders are being warned that cockroach infestations have soared this year with good breeding conditions and the winter's soggy, cold weather driving them indoors.

Dr Jacqueline Beggs of Auckland University says that insect populations are climate-dependent, and variable from year to year. In Auckland it appears to be an exceptional year for cockroaches.

Entomologist and television "Bugman", Ruud Kleinpaste, said the insects were cunning: "They'll come in with anything - cats or dogs, or even flower arrangements.

"And they are culture followers and waste-food lovers, so where there are humans, there will be cockroaches."

The effects of the cold and damp have sent eradication company business soaring. Jon Thompson, national technical manager for Rentokil Pest Control, said eradication jobs had doubled in the past 12 months.

Two of the six species found in the Auckland region are unique to the area. Most native species are found outside, under bark and on tree fronds. Those introduced from Australia, America and Europe are larger and more commonly found inside.

Arriving in New Zealand with Captain Cook, the most widespread pest cockroach in the world is the German species - they're the ones you see scuttling away from your benchtop when you switch on a light at night. They enjoy warm moist areas, such as kitchens, laundries and bathrooms.

American cockroaches are the largest, and prefer fermented food and wet areas, which means that they like sewers and drains.

Gisborne cockroaches aren't just found in Poverty Bay but were first identified there. They are natives of Australia, and arrived in timber shipments. They live under wooden decks and around firewood, and will hitch-hike inside with the wood or creep in through gaps.

If you find cockroaches, Landcare Research has a page on its website to help identify them.

To get rid of them you can buy a gel containing Imidacloprid from a pest control outlet, which should keep them at bay for months. Or you can call in a pest control firm.

But Mr Kleinpaste says even though we hate cockroaches, they do have a positive side. Because they live in filthy conditions, the insects coat themselves with an antibiotic - a discovery that scientists hope can be put to good use some day.

* Cockroach fact file

Cockroaches are members of the insect order of Blattaria.

The species dates back more than 300 million years.

The main pests in New Zealand are German, American and Gisborne cockroaches.

German cockroaches are yellowish-brown, and grow to 1.3cm-1.6cm long. They eat anything - grease, sugar and even soap - and turn to cannibalism if food is scarce.

American cockroaches grow to 5.5cm long and can run at speeds of 5.4km/h - for their size that is the equivalent of a human running at 330km/h.

Gisborne cockroaches are dark brown, with a white stripe along the sides. They are not as big a threat to public health as the German and American species.