Plague of mice threatens Australian crops

Press, 20 June 1984, Page 26

Plague of mice threatens Australian crops

NZPA staff correspondent Sydney Australian crop farmers are praying for a rugged winter, the colder and wetter the better, to help stem the growing tide of mice sweeping through their land.

Agricultural officials describe it as a plague, and say that unless the weather stops the mice now, nothing will hold them back from next summer’s crops. The mice are swarming through the crop areas of New South Wales, South Australia, and Victoria, and threatening to sweep north into Queensland in the wake of boom crops that followed the breaking of the fiveyear drought. Agriculture officers in the three states say that while the mice are still a lesser problem than great plagues of the past, they have the potential to become one of the greatest by next summer.

Mr John Griffiths, officer in charge of the Murray Research Station in northern Victoria, said that the mice were everywhere. “They are still not as

great as the big plague we had in 1979-80 - that one made this look like a pup — but if the winter doesn’t hit them they could be worse in the summer because the base level is higher. “Normally there might be 200 to a hectare, but now there are about 5000 to 6000 a hectare," he said. In New South Wales, the problem is every bit as bad with mice even attacking crops in the ground. A State agriculture department spokesman, Mr Mark Gortha, said they also numbered in the thousands per hectare in his state. Farmers are trying every sort of trap in the book and plenty that are not, including baits hung above buckets and drums of water.

That method is reported to be netting their inventors up to 600 mice a drum, while in South Australia farmers are said to be bulldozing up to 15,000 poisoned rodents each day into pits.

Trap-makers are having a field day and chemical producers are boosting supplies of the latest big bait poison, anticoagulants, that cause lethal internal bleeding in

the animals. Farmers in most states have given up trying to keep the mice out of pastures and crop paddocks where newly planted seeds are being eaten. Instead they concentrate on trying to keep them out of their houses, sheds, vehicles, and machinery.

Television viewers are being treated to news footage of virtual carpets of mice swarming every time a farmer moves a bag of grain. With wheat harvested in early summer, the main crops expected to be hit by the plague will be the sorghum, sunflower and barley crops. The main factor in making the damage less devastating than the plagues earlier this century is the expertise of the states’ grain storage authorities in keeping their silos rodent-proof.

Mice came to Australia with European settlers last century. Recent records show a plague of them at least every decade since 1903.

Agricultural officers say that the mice population explodes after a drought

when the survivors find increased supplies of fodder, seeds and insects. Their breeding habits go out of control, with each female producing litters of up to six every three weeks. The pests eat 10 per cent of their body weight every 24 hours and usually live for a year. Their wild predators, mainly snakes and hawks, cannot reproduce as fast and even farm cats and dogs are reported to have given up bothering to catch them.

The hope for the farmers, say the officers, is a cold winter with plenty of frosts. However, with the three states now in the grip of the early stages of a new drought, farmers are praying for rain. “If it came to a choice between mice and no rain, the farmers would take the mice plague,” said Mr Griffiths.

According to the experts, the plague can be expected to die out naturally by April when food supplies dwindle and the mice huddle together for warmth, transmitting diseases and resorting to cannibalism to survive.