Confirm what you are dealing with
German cockroaches are small (12–15 mm), tan, with two dark stripes behind the head, and breed indoors year round — they are the species behind most UK kitchen infestations. Oriental cockroaches are larger, darker and usually enter from drains, bin stores and basements.
Check warm, humid harbourage first: behind and under the fridge, the motor housing of the freezer, the void behind kickboards, inside cupboard hinges, around the boiler, and under the sink where pipework enters the wall.
- Live sightings in daylight usually mean a mature, crowded population.
- Pepper-like droppings and a musty odour confirm active harbourage.
- Egg cases (dark, ridged capsules) mean breeding on site, not a one-off hitchhiker.
Stop spraying before you bait
Aerosols and surface sprays kill the foragers you can see and repel the rest. Survivors move deeper into wall voids and appliance cavities, and the nest keeps producing. Worse, residual spray on or near a bait point makes cockroaches avoid the bait entirely.
If the property has been sprayed recently, wipe treated surfaces near your intended bait points with warm soapy water and let them dry before applying gel.
Apply gel bait where cockroaches actually travel
Gel bait works by transfer: a forager feeds, returns to harbourage, and the active ingredient passes through the population via droppings and cannibalism. That only happens if the bait is inside the runway, not on an open worktop.
Apply pea-sized dots (about 0.25 g) every 30 cm in cracks, crevices and hinge points. A 60 ml tube covers a typical kitchen and bathroom several times over across a treatment cycle.
Everything below assumes a professional-strength bait — our cockroach gel kits ship with the applicator and placement map referenced here.
- Cupboard hinges and the top inside corner of each cupboard.
- Behind the fridge, freezer, dishwasher and washing machine.
- Along the top edge of skirting boards and inside kickboard voids.
- Around pipework entries under sinks and behind the toilet cistern.
What to expect on day 1, 3 and 7
Day 1: sightings often increase. That is the colony sending more foragers to a new food source — it is the signal the bait has been found.
Day 3: activity drops sharply as bait transfers through the nest. Depending on infestation level this can happen inside 24–36 hours.
Day 7: sightings should stop. Keep bait in place; residual dots continue protecting the treated area and intercept any re-introduction.
Stop them coming back
Bait removes the population; hygiene and exclusion decide whether a new one establishes. Fix dripping taps and condensation, empty bins nightly, store dry goods in sealed containers, and seal pipework gaps with silicone or expanding foam.