How to Get Rid of Cockroaches in Your HDB or Home (Singapore)

Which cockroaches you are seeing

Two kinds turn up in HDB flats and condos. The small, light brown cockroaches, about the length of a fingernail, that run out of a kitchen cabinet or from behind the fridge when the light goes on are usually German cockroaches. They live and breed indoors, carry their egg cases with them and multiply fast, so a few sightings often mean a colony behind the kitchen fittings. The large, dark brown ones, up to 4 cm long, that appear near the floor trap, the rubbish chute or the bathroom are usually American cockroaches. They live in drains, pipe risers and chutes and come up into the unit looking for food and water.

The distinction matters because the treatment is different. A colony inside the kitchen needs baiting and residual treatment at the harbourage. Visitors from the drains need the drain and the entry routes treated and sealed. If the cockroach you saw was flying, the flying cockroaches guide explains what flight can and cannot tell you about the species and what to record.

If you are finding cockroaches specifically around your fridge, microwave or other appliances, the appliance cockroach guide explains the difference between external harbourage and an internal appliance problem.

Where they breed in HDB and condo kitchens

• Inside the cabinet under the sink, especially the gap where the pipes enter and the back corners
• Behind and under the fridge, stove, oven and dishwasher, where it is warm and grease collects
• Inside cabinet hinges, drawer runners and the kickboard void under base cabinets
• Around the rubbish bin and inside stacked cardboard boxes and paper bags
• Floor traps, sink drains and the kitchen and bathroom pipe risers
• The rubbish chute hopper and the service duct behind it

Look for small dark droppings like ground pepper, smear marks along edges, brown egg cases about the size of a grain of rice and a stale oily smell. These tell you where the activity is, which is what the operator needs to know. The cockroach egg cases guide explains what they look like and where to find them.

Gel bait or spray: why the order matters

An aerosol acts on the cockroaches it reaches. It does not reach egg cases or the insects sheltering in cabinet voids and wall gaps, so sightings can return. Spraying over an area that has already been baited can also contaminate the bait or keep cockroaches away from it, which is why UC IPM advises against spraying near bait placements.

Professional gel bait works differently. Small amounts are placed at the harbourage and feeding points found at inspection. Cockroaches eat it and some of the toxicant can pass to others in the colony, so bait can reach cockroaches that stay hidden. Baits act over time rather than on contact, and egg carrying females may not respond immediately, so a few sightings in the days after placement are normal. Residual treatment on suitable travel paths and drain treatment are combined with baiting where the assessment calls for it.

Kitchen hygiene steps that actually matter

Treatment works far better when the kitchen stops feeding them. Four habits do most of the work:

• Remove food and water overnight. Wipe grease off the stove and the splashback, wash or soak the dishes, dry the sink and wipe the pet bowl.
• Keep the bin lidded and empty it nightly. Rinse recyclables before they go in a bag.
• Store dry food in sealed containers and clear out cardboard and paper bags, which cockroaches both eat and lay eggs in. See the guide on pests in cardboard storage for what to check.
• Close the routes in. Keep floor trap covers in place, fit a sink strainer, fix dripping taps and seal the gaps where pipes pass through cabinet backs and walls.

None of this clears an established colony on its own, but it decides whether a treatment holds.

When to call a professional and what the treatment involves

It is worth getting help when you see cockroaches repeatedly, see them in the day, find droppings or egg cases, or have them in a kitchen or F&B space. This is what a Four Solutions cockroach treatment involves:

1. Assessment. Send photos, the property type, the affected areas and details of any previous treatment, and tell us about children, pets and food preparation areas. The team inspects the hiding places, the entry points and the conditions supporting the activity.
2. Treatment matched to the source. Depending on what is found, the team uses gel baiting, indoor residual spray on suitable travel paths and cracks, drain treatment, foam injection into contained voids, ULV fogging for larger spaces, or chemical free heat treatment where eggs, hidden harbourage or a sensitive space make it the right choice.
3. Preparation and return. The quote confirms the proposed method, the covered areas, the preparation and the return instructions for your household.
4. Warranty and follow up. Eligible cockroach treatment includes the existing 3 month warranty, subject to the assessed scope and the written conditions. Report continuing activity so the follow up can be assessed.

Cockroach treatment is quoted after a quick assessment because the scope depends on the property size and how severe the activity is. The pest control cost guide explains what affects the quote.

Cockroaches back after a treatment

Some activity in the first days after baiting is expected, because baits act over time and egg cases laid before the visit can still hatch. Activity that continues or returns usually has one of these causes:

• The food and water sources are still there, so new arrivals stay.
• A route in was not closed: an uncovered floor trap, a gap around a pipe, a chute hopper that does not seal. See the guide on cockroaches entering through the HDB rubbish chute for what to check.
• A neighbouring unit or the building drains carry a population that keeps sending visitors up.
• Bait placements were wiped away during cleaning or sprayed over, so they stopped working.

Keep a note of where and when you see them and send it to the team. The quote sets out what the follow up covers, and continuing activity in the covered areas of an eligible treatment is assessed under the written conditions of the 3 month warranty.

Further reading: UC IPM cockroach identification, monitoring and control; NEA prevention guidance for food premises; and NEA vector control operator information. These sources explain general principles; Four Solutions confirms the method for the individual property.

Cockroach FAQs

For tiny insects rather than an identified adult, use the baby-cockroach sighting record before choosing a method.