Rodents and mice are commensal pests: they successfully co-habit with humans, eating whatever food they can find and sharing the shelter of our buildings. Rodents contaminate more food than they eat and in so doing, many diseases are transmitted. In conjunction with the flea, rats were responsible for the deaths of 25 million Europeans from Bubonic Plague.

BIOLOGY

The three major pest species are the Norway Rat, the Roof Rat and the House Mouse.They are common in the major population centres of Australia and most countries of the world. As climatic conditions become less favourable during the onset of winter, rodents move indoors for both shelter and food. In commercial premises, rodents can be a year-round problem and mice can attain plague proportions in rural areas.

Nests are made of soft materials such as shredded paper or fabrics, close to areas where they scavenge for food and water.The female is capable of giving birth to 4-6 litters a year, each litter containing 5-10 young, which themselves are capable of reproduction three months after birth. Within a year, the progeny of a single pair of rodents can number 400-700.

Rodents actively forage for food at night using the same route to and from the food source. Their diet includes food material of both plant and animal origin, and, for rats, water is necessary. Mice can obtain enough water from food provided it’s moist enough.

Although the vision of rodents is poor, their senses of smell and taste are so highly developed they can detect minute quantities of chemicals in foodstuffs: this can lead to “bait shyness”. Their whiskers and guard hairs enable them to feel their way in their preferred darkness with little difficulty.

MANAGEMENT

Rodent activity is seldom observed during daylight hours, so it is important to recognise signs of their presence.They deposit their droppings on all surfaces over which they travel, and this together with stains caused by almost continual urination, provides obvious indications of a rodent presence. Greasy smear marks also become evident along their main routes of movement where they make contact with obstacles. Rodents are equipped with incisor teeth that continually grow, and it is essential they gnaw at frequent intervals to ensure these teeth are sufficiently short to enable them to feed and fight. Fire can result from the short circuiting caused when rodents gnaw electrical conduiting.

As with all pest management programs, an Integrated Pest Management (IPM) approach is an integral part of successful rodent control. IPM involves consideration of all control procedures, including attention to sanitation and hygiene, trapping, proofing of entry points and use of baiting procedures. All control procedures are preceded by a thorough inspection of the entire premises to identify the rodent and to define the extent of the infestation.