I saw one cockroach. Are there more?

Maybe, maybe not. One cockroach can be a stray that walked in from outside, came up a drain or rode in on a box. It can also be the one you happened to see from a group hiding nearby. You cannot tell from one sighting, but you can find out within a week or two, and you can start on the free fixes today.

And if you are worried about what it says about your home: cockroaches turn up in clean homes too. They come for warmth, water and shelter, and they travel between flats, in deliveries and in second-hand things.

What the one you saw can tell you

• A small, tan one with two dark stripes behind the head is likely a German cockroach. This is the one that breeds indoors, so take it seriously.
• A large, reddish one is likely an American cockroach, often in from drains or outside. One of these is more often a visitor.
• A young one (small, wingless) matters more than an adult. Young ones usually mean breeding close by.
• Seen in daylight can mean the hiding places are crowded. Cockroaches prefer the dark.

Not sure which one it was? Our four cockroaches side by side shows the tell for each.

Find out in a week or two

1. Look for signs tonight. With a torch, check under the sink, behind the fridge and cooker, inside low cupboards and along hinges. Droppings look like ground pepper or small specks; egg cases are small brown capsules. Our page on droppings and egg cases shows what to look for.
2. Put out monitor traps. These are folded sticky cards. Set them flat against walls where cockroaches travel: under the sink, behind appliances, in the bathroom. See how to use monitor traps.
3. Check them on the same day each week and write down what each trap caught, adults and young ones apart.

Empty traps after two weeks, and no droppings, is a good sign that you saw a visitor. Young ones on a trap, or catches that keep coming, mean there are more.

What to do while you wait

• Take away water. Fix the dripping tap, dry the sink at night, check under it for leaks.
• Take away food. Crumbs behind the cooker, grease, the bin, pet bowls left out overnight.
• Close the way in. Gaps around pipes under the sink, a missing kickboard, a floor drain without a cover. See sealing gaps.
• Skip the spray for now. Spraying the one you see does not touch the ones hiding, and it can push them deeper into walls, away from bait you may need later.

Kids and pets: sticky traps have no poison, but the glue sticks to fur and fingers. Put them behind the fridge or inside a cupboard a toddler cannot open.

If the traps say there are more

For the small indoor German cockroach, the standard approach is gel bait in small dots where they hide, an insect growth regulator so the young cannot become breeding adults, and the same traps to check progress. The German cockroach guide has the plan step by step. Follow the label on every product.

If you rent, tell your landlord or building manager in writing now, with the date and what you saw. Cockroaches move between flats, and a building problem needs the building to act.

When a clean inspection is not the end

A pest controller who finds nothing after one sighting is good news, but it is a snapshot of one visit. Keep the traps out for a few more weeks. If young ones appear later, you now have dated counts to show them, which helps far more than “I saw one”.