How do I know if I have German cockroaches?

Small tan insects 12 to 15 mm long with two dark stripes behind the head, seen near warm appliances or cupboard hinges, plus pepper-like droppings and a musty smell. Daylight sightings usually mean a crowded, mature population.

Why do German cockroaches come back after spraying?

Egg cases are carried by the female and are not affected by surface spray. Once the residue fades, the new generation matures and forages again. Bait keeps working residually, so emerging nymphs are dosed too.

How long does a German cockroach treatment take?

Activity peaks in the first hours, drops sharply across 24 to 36 hours, and a typical domestic infestation is finished within one to two weeks with a day 3 top-up of consumed dots.

Do I need to treat neighbouring flats too?

If neighbouring units show activity, yes. German cockroaches move along shared ducts and pipework, so coordinated baiting prevents re-invasion after your own treatment succeeds.

German cockroach treatment that clears the breeding population

The German cockroach is the species behind almost every UK kitchen infestation: small, tan, two dark stripes behind the head, and breeding indoors all year. Each egg case carries around 30 to 40 nymphs, which is why a treatment that only kills what you can see never finishes the job. The fix is bait inside the harbourage.

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Kills nymphs and adults through colony transfer
Breaks the breeding cycle, not just the visible foragers
Applied inside voids and equipment, out of reach
Sightings normally collapse within 24 to 36 hours

Choose your kit

Want the full range in one place? See all German cockroach gel bait kits.

German cockroach treatment options compared

What actually reaches a breeding population inside voids.

Option	Kills the nest?	Indoor use	Timescale	Verdict
Pest Tech Gel bait	Yes, including nymphs	Yes, hidden dots	24 to 36 hours	Best choice for a breeding infestation
Surface spray	No	Fumes and residue	On contact	Egg cases survive, infestation rebounds
Fogger	Rarely	Vacate the room	Hours	No reach into sealed harbourage
Boric acid powder	Partly	Messy in kitchens	Weeks	Slow, and easily avoided

Confirm it is a German cockroach

12 to 15 mm, tan to light brown, with two parallel dark stripes running behind the head. Found in warm humid spaces indoors: behind the fridge and freezer motor, inside kettle and toaster bases, cupboard hinges, under the sink, around the boiler. Larger, darker, drain-dwelling insects are Oriental cockroaches, treated the same way but baited nearer entry points.

Why the breeding cycle matters

A female carries her egg case until it hatches, protected from sprays. That means a spray-only treatment can look successful for two weeks and then fail as a new generation matures. Gel bait keeps working residually, so hatching nymphs feed on the same dots and are dosed as they emerge.

The treatment sequence

Stop spraying and clean any sprayed surfaces near your bait points. Apply pea-sized dots every 30 cm inside cupboard hinges, behind appliances, along skirting tops and kickboard voids, and around pipework. Leave the dots alone. Re-inspect on day 3 and replace anything consumed.

Flats, HMOs and terraces

German cockroaches travel between units along shared service ducts and pipework. If neighbours have activity, treat at the same time and bait every duct and pipe entry in your own unit, or the population simply re-enters after your treatment finishes.