Rats and mice

Rats and mice are types of rodents well adapted to living in close association with humans.

In low numbers they pose little health risk, however when found in large numbers they can damage structures, spoil and contaminate food and pose increased risks to human health.

Native Australian rodents, such as rakali or water rat, pose little or no threat to public health and should be left alone as they are protected species.

Common feral rodents in the ACT

Brown rat (Rattus norvegicus)

• Weight of 450g.
• Heavy set body.
• Blunt nose.
• Small ears.
• Course, red to brown hair.
• Tail is usually shorter than the body and the head.

Black rat (Rattus rattus)

• Weight of 260g.
• Slender body.
• Pointed nose.
• Large ears.
• Fine grey, black or brown hair.
• Tail is usually longer than the body and the head.

House mouse (Mus musculus)

• Weight of 15g.
• 7.5cm long.
• Grey, brown hair.
• Body shape is pointed at one end.
• Tail is about 8cm long.

Health risks posed by rodents

Feral rodents can:

• carry diseases such as leptospirosis which may be transmitted to humans through exposure to their urine
• contaminate food with their hair, droppings and urine, resulting in food poisoning and spoilage
• generate unpleasant odours
• carry fleas or ticks which may in turn transmit infectious diseases
• damage materials such as food containers, wood, particle board, insulation and wiring through gnawing.

Detecting signs of rodents

Rodents will shelter and nest in places such as homes, sheds, garages and gardens, particularly:

• in walls, ceilings and under floors
• behind or under cupboards or bathtubs
• behind or under fridges, freezers and dishwashers
• behind boxes, machinery and furniture
• in rubbish heaps, wood piles, thick vegetation, animal enclosures, paper or cloth
• in holes under buildings.

Rodents are generally more active at night and are more commonly seen in late summer or early autumn. If you see rodents during the day, this usually indicates high numbers or that there is a good food supply nearby.

When inspecting for rodent activity, look for the following:

• black, moist, thin droppings inside or around the property
• urine odours
• squeaking, gnawing or movement noises in the walls, cupboards, ceilings and under floors
• a worn path where they have developed a ‘run’ that leads to their shelter
• greasy marks along the paths they travel
• burrow holes around buildings, fences or concrete slabs
• signs of gnawing damage on fruit and vegetables or materials such as wood, insulation and electrical cabling
• nests, including in hidden areas, made up of a wide range of materials such as cardboard, paper and straw
• pets that are more excitable than usual.

Precautions

If you find signs of rodents, you can take immediate action to help reduce any health risk to you and the occupants of your property:

• secure all foodstuffs in tightly sealed containers
• throw away food or drink that may have come into contact with rodents or their urine or faeces.
• wash cookware and cutlery in warm soapy water before use.
• wash hands thoroughly before preparing food, eating or drinking.
• wear shoes and do not lie or sleep on areas where rodents have been active.

If you are bitten by a rat or mouse, consult your doctor promptly.

Preventing rodent habitation

Rodents are well adapted to living in human environments and while total elimination of rodents may not be possible, removal of conditions which help harbour rodents can be the most effective means of managing their activity.

You can do this by:

Removing food and water sources

• Dispose of food scraps promptly and clean food preparation areas thoroughly.
• Ensure rubbish bins have tight-fitting lids and are regularly emptied.
• Dispose of fallen fruit and seeds and waste from aviaries and chicken pens.
• Remove seed from wild bird feeders.
• Do not use open compost heaps and do not compost any animal products (fish, meat, chicken, cheese, butter) or pet faeces.
• Leave out just enough pet food for pets to eat soon after it is placed there.
• Store pet and poultry food in vermin proof containers with close-fitting lids.
• Cover rainwater tank openings and floor vents with vermin mesh and check and maintain these regularly.

Removing shelter

• Inspect living and working areas for potential rodent entrances and block them where possible with concrete, hard setting filler, steel wool or heavy gauge sheet metal.
• Keep your home and property clear of rubbish.
• Keep stacked materials such as wood and bricks at least 30 cm above the ground to minimise hiding, nesting, and thoroughfare of rats and mice.
• Regularly clean out sheds and storage areas and dispose of unwanted items.
• Remove unwanted undergrowth – cut back grass, trees, bushes, and creepers which may provide cover or access to the roof.
• Block access points to cupboards containing food and food-preparation utensils.

Treating a rodent problem

Trapping

Mouse and rat traps differ in size and strength, so it is important to identify the type of rodent before determining the most suitable trap to be used. Traps can be bought from hardware stores or supermarkets.

• Several traps should be used at one time.
• Do not set traps near food preparation areas.
• Place traps across ’runs’ for a few days before setting to allow rodents to get used to the traps.
• If you have children or pets which may be exposed to traps, consider traps that are child and pet safe in design and fully enclose any trapped rodent.
• Traps can be successfully set with bacon, peanut butter, fish, meat, bread or chocolate. Contrary to popular belief, cheese is not an effective bait as some species of rodents find the scent of cheese unappealing.
• Check traps daily and remove any dead rodents and refresh the bait. See how to dispose of rodents below.
• Use an insecticidal surface spray around the immediate area to kill any fleas which may leave a trapped rodent’s body.

Baiting and poisoning

Chemical control should only be considered as part of a broader control program of eliminating food sources and rodent harbourage. Chemical control is generally short-term, and rodents will return if food and shelter are still available.

If you do decide to use a chemical control method, you should consider:

• if rodents die and decay in hard-to-reach places they may cause an offensive odour
• pets and children may eat toxic baits or poisoned rodent bodies
• some individuals are sensitive to rodent control chemicals in their environment.

If you use chemical control

• Read the product label prior to use and only apply pesticides in accordance with the label directions including any safety information.
• Wear appropriate Personal Protective Equipment (PPE) as directed by the pesticide manufacturer (for example, gloves and respirator) when handling pesticides and ensure PPE is washed or disposed of after use. Always wash your hands thoroughly after any handling of chemical control agents.
• Baits should be placed (and stored) in locations away from open spaces that cannot be accessed by children, pets, wildlife or livestock, and/or use lockable bait stations.
• Place baits only in locations from which they can later be retrieved.
• Keep a record of bait placements.
• Inspect bait stations regularly and remove baits if the rodent problem ceases, ensuring appropriate disposal.
• Notify all occupants of the building about the use of pesticides.
• Do not place baits or tracking powder where they can cause food contamination.
• Do not eat, drink or smoke when handling pesticides.
• Store pesticides in their original containers and ensure that the label remains intact.

Extreme care must be taken when using poisons and you should read instructions carefully to prevent danger of children or pets being accidentally poisoned.

Poisons hotline

Should you be concerned that a child or pet has come into contact with a chemical control agent call the poisons information line on 131 126 at any time and follow their advice.

Disposing of dead rodents

Wear gloves and clothes that cover bare skin and use a shovel, rake or dustpan to collect dead animals. Covering exposed skin will help avoid contact with any body fluids and dust from the dead animals.

Dead rodents can be buried or wrapped and placed into a domestic rubbish bin to prevent pets or native animals having access to them. Remember to wash your hands with soap and warm water immediately after handling.

Professional pest controllers

Contact a professional pest controller if you aren't comfortable dealing with rodents.

Go to Access Canberra to search for professional pest controllers.

Rodent action plan

If you are seeing concerning signs of increasing rodent activity on your property, the rodent action plan provides advice on how to respond.

Insanitary conditions investigations

Due to their success in living alongside humans, rodents are present throughout Canberra and the built environment. As a result, it is unrealistic to eradicate all rodents.

Small numbers of rodents are likely to exist in your neighbourhood, despite all the above measures being undertaken. When rodents are at low numbers in your neighbourhood, the risk to human health is low.

If you are concerned there is a rodent infestation in your area, you should talk to your neighbours to remove sources of food and shelter.

If this doesn't help, you can contact the Health Protection Service who can investigate whether an insanitary condition is being created under the Public Health Act 1997.

An insanitary condition is a condition which represents a public health risk and is only likely to exist where large rodent populations exist (such as infestations), and rodents are coming into close contact with humans.

Owners and occupiers of premises are required to take reasonable precautions to prevent rodents living and breeding on their property at levels which may cause insanitary conditions.

For more information on insanitary conditions, email the Health Protection Service at hps@act.gov.au or phone 02 5124 9700.