Cockroaches in your flat: how to spot them, get rid of them and keep them out

They scurry off the moment the light goes on and vanish behind the fridge or under the sink: cockroaches. Finding cockroaches in your flat often feels embarrassing, and the first reflex is to grab an insect spray. Neither is necessary. Cockroaches are not a sign of a dirty home, and spray doesn't solve the problem – at most it drives them somewhere else.

In Switzerland the culprit is usually the German cockroach, a warmth-loving species that settles in homes for good. This guide explains how to recognise an infestation, who to tell, what the pest controller does and how cleanliness and vigilance help prevent it. It is no substitute for professional pest control.

Why cockroaches end up in your flat

Cockroaches don't come because of dirt; they are carried in or move in from next door. In its fact sheet (in German), the City of Zurich explains that the German cockroach is brought in with luggage, used furniture, second-hand appliances or packaging and spreads from flat to flat along pipes and ventilation shafts. It is nocturnal and hides in warm, damp spots: the kitchen, the bathroom and behind appliances.

Not every cockroach is a problem. The native forest cockroach occasionally flies in through an open window in summer. According to the City of Zurich, it is harmless, cannot breed indoors and dies within a few days, so there is no point in controlling it. An insect screen keeps it out.

1. Spotting cockroaches: signs and sticky traps

Because cockroaches stay hidden during the day, an infestation is often noticed late. Look out for these signs:

• Droppings: small dark specks that, according to the City of Zurich, look like coffee grounds, often in drawers, cupboard corners and behind appliances.
• Night-time sightings: insects fleeing into cracks when you switch on the light.
• Shed skins and egg cases: light brown casings in corners and gaps.
• Smell: with a heavy infestation a musty, sweetish odour can develop.

Sticky traps placed against the wall and skirting behind the fridge, cooker and sink show whether and where cockroaches are active. They are a monitoring tool, not a treatment. Note where and when you found insects – the pest controller will find it useful.

2. Tell property management and your neighbours

As cockroaches travel through service shafts, an infestation rarely affects just one flat. The City of Zurich advises talking to the neighbours and having the whole building treated at once by a professional pest controller via the property management. If you treat only your own flat, the insects may simply come back from next door.

So report the infestation to property management, ideally in writing with photos of insects, droppings or traps. According to the fact sheet, if the cockroaches were already there when you moved in, it is a rental defect that the landlord must fix. There is no need to feel ashamed: an infestation can affect any home.

3. Leave the treatment to a professional

The actual control is a job for a professional pest controller. They identify the species, usually place targeted food baits and check the results over several visits, as new insects can hatch from egg cases.

Your part as a resident:

1. Follow the pest controller's instructions exactly, including on tidying and cleaning.
2. Empty and clean kitchen cupboards and surfaces before the appointment as agreed.
3. Don't wipe away the baits or wet them with cleaning products.
4. Keep noting and reporting new sightings and trap catches.

4. Make the kitchen and bathroom hostile to cockroaches

Cleanliness alone won't drive cockroaches out, but it deprives them of food and water and supports the treatment. The Federal Food Safety and Veterinary Office points out that germs spread via hands, chopping boards, utensils and cloths and that worktops and utensils should be cleaned with hot water and soap after each step. Since cockroach droppings can spread germs and allergens, this matters all the more now.

• No leftovers overnight: wash up, wipe away crumbs, put pet food away in the evening.
• Seal food supplies: tins or jars with lids instead of open packets.
• Empty the bin daily and wash the lidded bin regularly. Tips in our guide Bin smells in summer.
• Reduce moisture: wipe the sink and draining board dry in the evening and report dripping taps to property management.
• Remove grease films: clean cupboard fronts, plinths and the areas behind appliances thoroughly. Our guide on how to clean greasy kitchen cabinets explains how.
• Get rid of cardboard: corrugated cardboard offers hiding places and egg-laying sites.

5. Prevention: stop cockroaches being brought in

The best control is not to let them in in the first place:

• Check used furniture and appliances: inspect second-hand fridges or coffee machines before bringing them indoors, especially cracks and the motor compartment.
• Check luggage after trips before unpacking in the kitchen or wardrobe.
• Don't hoard packaging: unpack delivery boxes quickly and put them out with the paper recycling.
• Have gaps and openings sealed: gaps around pipes behind the sink and WC are highways. Tell property management.
• Insect screens against forest cockroaches and other insects, especially in summer.

The same measures help against other unwanted housemates too, such as silverfish.

The most common mistakes with cockroaches in your flat

• Keeping quiet out of embarrassment: without property management and the neighbours, the infestation comes back.
• Using spray: the insects flee into other rooms or flats and the problem just moves.
• Cleaning away the baits: wet-cleaning treated spots makes the treatment ineffective.
• Fighting forest cockroaches: a few single insects in summer are harmless – opening the window or putting them outside is enough.
• Bringing in second-hand appliances unchecked: a common way for cockroaches to move in.

Priority Clean editorial teamOur cleaning team from Alberswil, Canton of Lucerne, shares hands-on experience from move-out, house, office and window cleaning across Central and Northwestern Switzerland.