A bloke at Albion Park had been at it for six weeks before he called me, and he was not in a good mood about it.
Two snap traps and four bait stations, all of it along the back fence and down the side of the shed, checked every second morning. Nothing touched. Meanwhile something was still getting into the pantry, and his wife had found droppings in the cutlery drawer, which is the point at which these calls usually get made.
The droppings were mouse droppings. They'd been mouse droppings the whole time. He'd spent a month and a half running a textbook rat program against an animal that was living behind the oven and had, as far as I could tell, never been in the back yard in its life.
That's the most common way a DIY rodent job fails around here. Not the wrong product. The wrong animal.
The droppings tell you before anything else does
You'll see the droppings long before you see the animal, so start there.
A mouse dropping is about the size of a grain of rice, pointed at both ends, and there will be a lot of them scattered fairly randomly. A black rat leaves something closer to a small sultana, dark and blunter, and you'll usually find them concentrated along a run rather than sprinkled everywhere. Once you've seen the two side by side you'll never mix them up again.
The size difference in the animals themselves is bigger than people picture. The Australian Museum puts the House Mouse at a body of 60 to 100 millimetres, a tail about the same length as the body, and a weight of 10 to 25 grams. The Black Rat runs 165 to 205 millimetres in the body, a tail longer again than head and body together, and anywhere from 95 to 340 grams. A well-fed black rat can weigh what a dozen mice weigh.
You can hear the difference too, once you know to listen for it. A mouse in a ceiling is a light quick skitter, and it stops and starts. A black rat is a weight moving across the plasterboard, and there's often a dragging or a rolling noise with it. Half my phone diagnoses are made on somebody holding the phone up to the ceiling at nine at night.
One thing worth clearing up: despite the name, a black rat is usually brown or grey. The museum says so outright. I've had people rule out rats because "it was brown", which rules out almost nothing.
Two animals, two completely different jobs
This is why the ID isn't trivia.
Black rats are climbers. The museum describes them as very agile climbers that live in roofs, cavity walls and trees, and that's exactly what I find: the animal is nesting in your roof void or up a tree and commuting down to feed. So a rat job is a roof-and-perimeter job. The overhanging branch touching the gutter. The gap where the fascia has dropped away. The lifted tile over a valley. The service cable that runs into the eave. Get the roof void and the outside right and you've done most of the work.
House mice are the opposite. The museum's description has them living in secluded parts of buildings and in cracks, making nests out of shredded material, and closely associated with people. They aren't commuting from anywhere. They're already inside, behind the dishwasher, in the wall cavity behind the pantry, up in the insulation over the kitchen, and their whole world is a few metres across.
Which is exactly why the Albion Park job failed. A mouse living behind an oven is not going to walk twenty metres down a lawn to find a station on the fence. It doesn't need to. It's got a cereal box.
Put simply, a rat job mostly happens on the outside and up high. A mouse job mostly happens on the inside and low down. Run one against the other and you can work very diligently for six weeks and achieve nothing at all.
The juvenile trap
There's one honest source of confusion I'll own up to, because it catches people who are otherwise doing everything right.
A young black rat looks like a mouse. The museum notes juveniles are sometimes mistaken for mice, and in a torch beam at night I'd want a proper look before I committed either. The tell is proportion: on a juvenile rat the head and the back feet look slightly too big for the body, like a puppy. A mouse is in proportion. Ears help as well. A mouse has large rounded ears on a small head with rather bulging eyes; a black rat's ear is large and thin and, bent forward, reaches the middle of the eye.
If you're not sure, the safe assumption is rat, because a rat program placed for rats will still deal with mice that wander through it, and the reverse is not true.
Why "I've only seen one" is never one
Both of these breed faster than feels reasonable.
A house mouse can breed at two months old with litters of four to eight. A black rat has litters of about five to ten and can have up to six litters a year, with the young weaned at twenty days. Neither of those is a number you can outrun with a trap on the floor of the pantry.
It also means timing matters. Autumn and early winter push everything indoors looking for somewhere warm, so the call volume climbs from about April, but the population that arrives in autumn was built over summer. The cheapest rodent work is done in late summer before anything moves in.
Why the bait you bought didn't work
Assuming you got the animal right, a few other things reliably sink a DIY attempt.
Rats are wary of anything new in their environment. A station that goes down on a Monday can sit untouched until the following weekend simply because it wasn't there before. People pull them up on day three, decide the bait's no good, and buy a different brand, which resets the clock. Mice are the opposite and will investigate a new object the first night, so if a mouse hasn't touched a station in a week, the station is in the wrong place rather than being ignored.
The loose bait block on the pantry floor is the other one. It's in the wrong place for either animal, and it's reachable by the dog, the cat and a curious two-year-old. Bait belongs in a tamper-resistant, lockable station sitting on an actual run, which is one of the reasons a rodent job involves finding the runs first.
Then there's the trade-off nobody mentions until it happens. Bait an animal that's living inside a wall and there's a decent chance it dies inside that wall, and you've swapped a noise for a smell you can't locate. It's a real risk, it's manageable with placement rather than luck, and the whole business of where the smell goes and why it moves around the house is in why a dead rodent never smells where it actually is.
What a rodent job actually looks like
The first visit is mostly looking, and if somebody starts putting bait down before they've worked out what you've got and where it's running, that's a bad sign.
I want droppings, gnaw marks, the greasy rub marks along a bearer or a top plate where an animal has been using the same route nightly, and the roof void, because in an older Illawarra house that's where the answer usually is. From there the placement is decided by the animal: stations and traps on the runs for a rat, interior work close to the harbourage for a mouse, and in both cases something that isn't accessible to pets or kids. What that covers is on the rat and mouse control page.
Then the part that decides if you'll be doing all this again next winter. Sealing the way in. Neither animal needs much of an opening, and our older housing stock is generous with them: weep holes, subfloor vents that lost their mesh decades ago, the hole where a pipe goes through a wall, a roller door with no brush seal, a fascia that's pulled away from the rafter. The full walk-around, gap by gap, is in rodent-proofing an older Illawarra home, and it's the one part of this you can genuinely do yourself on a Saturday.
Do the proofing and the treatment holds for a long time. Skip it and you're buying the same job annually, which is a fine business model and a rubbish outcome.
Back to Albion Park
We found the nest in the insulation above the kitchen, shredded cardboard and a bit of pink batt, roughly where you'd expect given the oven. It was mice, plural, as it always is.
The traps came off the fence. The work went inside and along the base of the kitchen cabinetry, and the entry point turned out to be a gap around the gas line behind the stove that you could see daylight through if you got your head down low enough. That gap had been there since the kitchen was done.
He asked me, fairly, why nobody had told him to check the droppings first. So: check the droppings first. Rice grain or sultana. It's ten seconds and it decides the entire job.
If you're hearing something in the ceiling and you'd rather not spend six weeks finding out what it is, send us a photo of the droppings or give us a ring and describe the noise. It's usually enough to know what we're dealing with before anyone turns up.
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