Hitching a ride
German cockroaches are small, flat and content in any warm crevice, which makes them easy to carry between buildings without anyone noticing. One female tucked into a box can be enough to start a population, because she brings her egg case with her. It is also why their arrival says little about housekeeping — see do cockroaches mean a property is dirty.
Deliveries, boxes and cardboard
Corrugated cardboard is a favourite refuge: the channels are dark, the starchy glue is edible and the boxes travel between warehouses, shops, kitchens and homes. Grocery deliveries, bulk packs of food and crates brought into food businesses can all carry cockroaches. Unpack deliveries promptly and avoid keeping flattened boxes in the kitchen.
Second-hand appliances and furniture
A used fridge, microwave, toaster or coffee machine from a kitchen with cockroaches can bring them straight into yours, eggs included. Look at the back, the vents and the underside of anything second-hand before it comes indoors, and clean it thoroughly. Wooden kitchen units and shelving deserve the same inspection.
Luggage, bags and moving home
Suitcases, shopping bags and boxes packed in an affected property can take insects to a new address. If you are moving home — to or from Cricklewood or anywhere else — unpack kitchen items first and watch for droppings over the following weeks. Fleas left behind by previous occupants are another surprise, as flea problems after moving into a new home explains.
Inspecting something before it comes in
- Tip boxes out over a pale surface outdoors and look for droppings, egg cases or live insects
- Shine a torch into the vents, seams and motor space of a used appliance
- Check the folds of bags that have been stored in another kitchen or a storeroom
- Break down cardboard outside and put it straight into the recycling
- Clean second-hand items before they go anywhere near the kitchen
From neighbouring properties
In terraces, blocks and buildings with shops below, cockroaches cross between homes through ducts, pipe runs, wall cavities and floor voids. A neighbour moving out, clearing a kitchen or spraying their own home can send insects looking for new shelter, and the nearest warm, damp space may be yours. That route has its own guide: can cockroaches spread between flats.
Drains and under-floor voids
Oriental cockroaches live in drains and sewers and can come up through damaged drain connections, gaps around waste pipes and floor gullies. A sink or shower trap that has dried out in an unused room also leaves a way through. Ground-floor kitchens and basements are most exposed, and the same defects can let in rats — see can rats enter a property through drains.
Gaps around pipes, doors and air bricks
Less often, cockroaches walk in from outside through gaps under doors, around the points where pipes enter the building or through broken air bricks. This is more likely with Oriental cockroaches in warmer months, since German cockroaches seldom live outdoors. Houses with suspended timber floors, such as those in Willesden, have air bricks venting the void below, and a broken grille can give Oriental cockroaches a way under the floorboards.
Commercial premises
A food business takes in goods every day and often shares a building, so the chance of cockroaches arriving never really goes away. Commercial premises in Park Royal and elsewhere should check deliveries on arrival, keep storerooms orderly and act at the first sign. Commercial cockroach work is quoted per site.
Blocking the routes
Inspect things before you carry them in, repair leaks and drains, keep traps topped up with water and seal gaps around pipes; preventing cockroaches from returning goes into more detail. If they are already inside, cockroach control in Brent costs £190 for a flat and £240 for a house — book cockroach control to get started.
