Cockroaches: the specialist's complete guide
One cockroach seen at night means a hidden colony nearby, somewhere warm and damp.
Guide 03
Blattella germanica
Key points
In flats and restaurants alike, the most common cockroach is the German cockroach (Blattella germanica): 10 to 15 mm, light brown, with two dark stripes behind the head. It lives in hidden colonies close to warmth and water, breeds fast and carries germs. Lasting treatment means locating its harbourages first, then applying targeted gel bait and checking the result with monitoring traps.
Four species share the homes and businesses of Île-de-France. The German cockroach, by far the most common, colonises kitchens and bathrooms. The oriental cockroach, very dark brown to black, larger and slower, prefers cellars, bin stores and damp ground floors. The American cockroach, up to 4 cm and reddish-brown, frequents sewers, heated basements and large kitchens. The brown-banded cockroach, smaller and crossed by two pale bands, settles in drier rooms: bedrooms, behind picture frames, inside electronic devices.
Why the kitchen? Because it offers everything a cockroach needs: warmth (fridge, dishwasher and oven motors, water heaters), water (traps, sink seals, condensation) and crumbs. By day the colony packs into cracks a few millimetres wide: cabinet hinges, the underside of worktops, skirting boards, service ducts. You only ever see a small part of it, and almost always at night.
The female German cockroach carries her egg case (ootheca, around thirty eggs) attached to her abdomen until it is almost ready to hatch. The eggs are therefore shielded from most products, and a new generation can appear a few weeks after a superficial treatment. Depending on temperature, a nymph reaches adulthood in about two months, so a population can build up very quickly.
Shop-bought sprays and foggers often scatter the colony rather than eliminate it: cockroaches flee to other rooms or neighbouring flats. Some populations have also learnt to avoid poorly chosen baits, or become less sensitive to insecticides used over and over. Hence our rule: locate the harbourages before treating, rotate active ingredients and check the outcome with monitoring traps.
Spotting signs of cockroaches
- 1Tiny black specks, like coffee grounds or ground pepper, in hinges, cupboard corners and behind appliances.
- 2Empty brown egg cases (about 8 mm), pale moulted skins and dead insects under furniture.
- 3Cockroaches darting into a crack when you switch on the light at night, especially near the sink and fridge.
- 4Very small wingless young cockroaches out in daylight: a sign the colony is already dense.
- 5A stale, rancid smell in heavy infestations.
- 6Dark smudges around the small openings where the colony shelters.
Nuisance level
An indicative guide from our technicians, from 1 (moderate) to 5 (high).
- Health
- 4/5
- Damage
- 1/5
- Breeding
- 5/5
Why act
- Germs (including salmonella) carried on legs and bodies and left on worktops, dishes and food.
- Allergens in droppings and moulted skins, a recognised asthma trigger, particularly in children.
- Spread from flat to flat via ducts, water risers and rubbish chutes: treating a single home in an affected building gives fragile results.
- For food businesses and restaurants: non-compliance at a hygiene inspection and damage to reputation.
- Day-to-day stress, especially for tenants moving into a home that is already infested.
Our treatment, in four stages
- 01
Locate
Locate: torch-in-hand inspection of warm, damp areas (appliance motors, under the sink, skirting boards, ducts, false ceilings), species identification, sticky monitoring traps and a map of harbourages.
- 02
Treat
Treat: targeted pest control with gel bait applied in small spots in the cracks where the colony lives, supplemented as needed by an insect growth regulator, spot spraying or dry steam; no needless blanket spraying in living areas.
- 03
Check
Check: follow-up visit built into the protocol to reach the young that hatch from egg cases, monitoring traps read, product or gel placement adjusted if activity remains.
- 04
Prevent
Prevent: photo report emailed to you, gaps sealed (joints, ducts, traps), hygiene and storage advice, monitoring traps left in place for active vigilance.
Good everyday habits
What you can do to lower the risk of a new infestation.
- Leave no dirty dishes, crumbs or full pet bowls out overnight.
- Fix leaks, dry the sink in the evening and plug rarely used drains: water draws them as much as food.
- Take the rubbish out every evening and use a bin with a lid.
- Unpack delivery or removal boxes outside the kitchen, and check second-hand appliances before installing them.
- Seal cracks around pipes, behind skirting boards and under the worktop with silicone.
- After a gel treatment, don't wipe away the gel spots or spray insecticide nearby: it makes the bait less attractive.
Your questions
Is “cafard” the same as “blatte”?
Yes. In French, “cafard” is the everyday word and “blatte” the term professionals use; both mean cockroach. What matters for treatment is the species, since each one has its own hiding places and habits.
How long before I see results?
With well-placed gel bait, activity usually drops markedly within two to three weeks. The protocol recommends two visits: the follow-up targets the young that hatch from egg cases after the first treatment.
Will I have to move out while you treat?
Not for a gel treatment: the product is placed in small drops inside cracks, out of reach of children and pets. If spot spraying is needed, we tell you how long to stay out and air the room.
Does having cockroaches mean my home is dirty?
Not necessarily. Cockroaches often arrive in boxes, shopping bags or a second-hand appliance, or through the ducts of a building. A well-kept kitchen slows them down, but it won't get rid of a colony that is already there.
Why aren't insecticide sprays enough?
They mostly hit the insects you can see, not those hidden in cracks or the eggs protected inside their case. They can also drive the colony into other rooms or next door.
The whole building is affected: what should we do?
A coordinated treatment of the affected flats and the common parts (ducts, rubbish chutes, bin stores) gives better results. We work for individual residents as well as for managing agents and landlords.
How much does a cockroach treatment cost?
The price is shown including VAT before you book and depends on the floor area; it starts at €150 including VAT for the first visit. Payment is made online before the visit, and the photo report is emailed to you the same day.
Cockroaches in your home or your business?
Flat, house, restaurant, shop or office: price including VAT shown before you book, 2-hour window, same-day photo report and advice to lower the risk of a return.