The best rat traps for large rats

What "large" actually means here

Two species turn up in and around houses, and they are not the same size.

Roof rats are the slimmer climbers — typically 150-250 g, long-tailed, and usually found high: attics, rafters, trees, upper floors.

Norway rats are the heavy ground-dwellers — commonly 300-500 g on good feeding, thick-bodied, burrowing under decking, sheds and compost heaps. This is the animal people mean by "large rat", and it is the one that exposes an underpowered trap.

A trap sized for a roof rat may fire on a big Norway rat and fail to kill it. That is the failure this page is about.

Why force matters more than anything else

A trap that fires but does not kill produces three bad outcomes at once:

1. The animal suffers, sometimes for a long time.
2. It escapes, often dragging the trap.
3. Every rat that witnesses it becomes trap-shy, which can cost you weeks. Trap-shy rats is the recovery process, and it is much harder work than getting the trap right first time.

So on a confirmed large rat, buy for spring force and build quality rather than for a multi-pack price. A metal-bar trap holds more energy than a moulded plastic jaw, and it keeps holding it after repeated cycles.

Anchor it

This is the step people skip, and with a heavy animal it matters.

A 400-gram rat that is caught but not immediately killed can move a loose trap a surprising distance — under a shed, into a wall void, somewhere you will find it later by smell. Anchor every trap set for large rats:

• Wire the trap to a fence post, a joist, a pipe or a brick.
• Or set it inside a weighted, anchored station, which solves this and the weather and the pet problem at once. Best bait stations covers which boxes genuinely lock.
• Outdoors, a self-resetting trap mounted nose-down on a post keeps the carcass under the unit rather than letting it travel.

Bait it so it cannot be lifted

A big rat is strong and dexterous enough to take a loose bait off a trigger cleanly. That teaches it the trap is a feeder.

Tie the bait on: a loop of cotton thread around a strip of bacon or a piece of dried fruit, tied to the trigger pedal itself, with a smear of peanut butter over the top for scent. The rat has to pull, and pulling is what fires the mechanism. Best rat trap bait.

Pre-baiting still applies — more so

Large, established rats are usually old rats, and old rats are the most neophobic of all. Give them longer than the standard three nights:

• Five nights unset, baited and refreshed daily.
• Then arm everything on the same evening.
• If the bait is untouched after three nights, the trap is off the run — move it to where the greasy rub marks are, not to where you saw the rat.

Sizing the whole set

• Six traps on an active run as a baseline; more where activity is heavy.
• Full-size metal-bar traps on the ground runs, inside anchored boxes.
• An electronic trap where you would rather not handle the result — a garage, a cellar, a crawl space.
• A self-resetting trap if pressure outdoors is continuous and a daily round is unrealistic.

When to stop and call someone

A burrow system under a structure, a colony inside walls you cannot open, or activity that returns within weeks of every treatment is a professional's job. So is a large droppings clean-up in an unventilated crawl space — that is a respiratory-protection problem before it is a pest problem. How to get rid of rats covers where that line sits.