The Different Types of Rats in Melbourne

Key takeaways

Roof rats are strong climbers and are commonly found in roofs, ceilings, wall cavities and trees around homes.

Norway rats prefer ground-level areas, including sewers, subfloors, burrows, drains and areas near rubbish or water.

House mice can also become a serious pest problem, entering through very small gaps and nesting inside walls, ceilings, cupboards and other hidden areas.

Different rodents require different control methods, so identifying the pest can help determine the right treatment approach.

1. Roof Rats

They are also known as the black rat, ship rat, and house rat. These roof rats are the roof invaders. Here’s what you need to know about them:

Tail is longer than the body

Slim body that is 16–20 cm (excluding tail)

Colour can be grey-brown to black

Their average lifespan can take 9–12 months.

They can squeeze through holes as small as 1.2 cm.

They are highly known for their agility and curiosity.

Roof rats breed all year round in warm climates.

Female rats can produce 4–6 litters per year, with 6–10 pups each.

Their maturity is reached in 3–4 months.

They are called omnivorous types of rats. Roof rats prefer fruits, grains, nuts, and occasionally insects. They tend to nibble at multiple food sources rather than consume one completely.

Roof rats are excellent climbers and are commonly found in roofs, ceilings, wall cavities, and attics. They're more likely to infest upper levels of buildings and often nest in trees or dense vegetation around homes.

They have strong teeth that don’t stop growing. Roof rats, or black rats, can cause structural damage by gnawing on wood, insulation, and wires, posing fire risks. They contaminate food and spread dangerous diseases like salmonella and leptospirosis.

2. Norway Rat

They are called burrowing sewer beasts and also brown rats, sewer rats, common rats, and street rats.

They have a large, stocky body

Their size is up to 28 cm (head and body), with the tail shorter than the body

Shorter tail not longer than the body

Their colour is brown to grey

Norway rats are strong swimmers and burrowers.

They are typically active at night.

Notorious for digging and can chew through concrete and lead pipes

Norway female rats can produce up to 12 litters per year.

They can multiply 8–12 pups per litter after

Known as the rapid breeders with potential infestations growing fast

They are known for sewer beasts. Norway rats are terrestrial and prefer lower levels, including basements, sewers, subfloors, and burrows. They’re notorious for digging extensive tunnel systems and are commonly found near rubbish bins, drains, and wet areas.

They live underground, so most likely they eat nearly anything: meat scraps, garbage, grains, pet food, and even small animals.

Norway rats are commonly more aggressive than their black cousins. They are known to undermine building foundations, contaminate food, and transmit diseases like rat-bite fever, Weil’s disease, and plague.

If you want to eliminate them, you must focus on ground-level baiting, burrow treatment, and proper waste disposal. Physical exclusion through concrete barriers or mesh is highly effective.

3. House Mice

House mice are the silent invaders. Also known as the common mouse or field mouse. Don't be fooled by their size; house mice are just as destructive as their larger cousins. These tiny pests reproduce quickly and silently, often remaining undetected until a full-blown infestation takes over.

House mice are 6–9 cm from head to body, with a tail of similar length.

They have brown to grey colour.

They have pointed noses.

Their tails are thin and scaly.

You can notice that they have large and fine fur.

House mice are extremely curious and adaptable creatures.

They can build nests from paper, fabric, and insulation.

Can enter buildings through holes as small as 6 mm

House mice reach sexual maturity at just 5 to 6 weeks old and can begin breeding almost immediately after weaning.

Their gestation period begins only 19 to 21 days or around 3 weeks.

They typically produce 5 to 8 pups, but can range up to 12 litters.

The weaning period of a house mouse is about 3 weeks after birth.

A female mouse can become pregnant again within 24 hours of giving birth.

Inside walls and ceilings

Inside pantries, cupboards, and drawers

Commercial kitchens and food storage areas

Grains, cereals, chocolate, dry goods, pet food

Nibbles small amounts from many sources

They contaminate food through their droppings and urine.

Can damage insulation, furniture, and wiring

Spreads diseases such as lymphocytic choriomeningitis virus and salmonella