Cockroaches Identification Greenwich: What Signs Should You Look For?

The Two Species, Side by Side

That last row is the reason this article exists. A treatment aimed at the wrong species is a treatment aimed at the wrong part of the building.

The Adult Insect

German cockroach: small, pale to mid brown, with two darker parallel stripes running back from behind the head. Fast, and it heads for a crevice rather than a corner.

Oriental cockroach: larger, glossy, very dark - often described as almost black. No stripes. Slower and more likely to be found in the open at ground level, particularly near a drain or a door.

What both rule out: anything hard-shelled and domed is probably a beetle. Anything with long back legs that jumps is a cricket. Cockroaches are flattened, run rather than jump, and seek crevices.

Nymphs

What to look for: smaller versions of the adult without fully developed wings. German nymphs carry the same dark stripes, which makes them identifiable even when very small. Oriental nymphs are dark and glossy.

What it tells you: breeding on the premises rather than a single insect having been carried in. Finding nymphs raises the priority considerably.

Egg Cases

What to look for: a small, dark, purse-shaped capsule with fine ridges along one edge. German cockroach cases are usually carried by the female until close to hatching and so are found near harbourage; Oriental cases are dropped and may be found some distance away.

What it tells you: why a single treatment is not the whole job. The capsule is protective, so a treatment that deals with every live insect still leaves what is inside the cases. That is exactly what the follow-up visit is timed for.

Droppings

What to look for: small dark specks, often described as resembling ground pepper or coffee grounds. In cupboard corners, along the top edges of unit carcasses, behind and under appliances, and in the runs between harbourage points. Larger species leave larger, more cylindrical droppings.

What it tells you: where the runs are, which is where the treatment goes. A concentration along the underside of a worktop tells you far more than a sighting on the floor does.

What it rules out: spilled coffee or cocoa in a drawer is the classic false positive. Droppings are uniform in size and shape; spilled grounds are not.

Smell

What to look for: a musty, slightly oily smell, most noticeable when opening a cupboard that has been shut for a while.

What it tells you: a substantial and established population. It is a late sign rather than an early one, so its absence means nothing at all.

Where to Look, by Species

For German cockroach

1. Behind and underneath the fridge, especially around the motor housing.
2. Inside kitchen unit carcasses, particularly the corners and the top edges.
3. The underside of the worktop and the void behind the kickboard.
4. Around the dishwasher and washing machine, where pipework enters the wall.
5. The cavity around cabling and any warm appliance housing.
6. Behind a wall-mounted boiler.

For Oriental cockroach

1. Around drain covers, gullies and inspection chambers.
2. Bin stores and the ground beside them.
3. Basements, cellars and semi-basement rooms.
4. Boiler rooms and service ducts at ground level.
5. The threshold of an external door, particularly at night.

Four Things Mistaken for Cockroaches

• Ground beetles. The commonest by far - hard-shelled, domed, and they blunder rather than run for cover. Frequent in ground-floor flats with a door open in summer.
• Crickets. Long back legs and they jump.
• Larder and biscuit beetles. Much smaller, found in stored dry goods, and a completely different treatment.
• Woodlice. Segmented, slow, and they roll or curl rather than run. A damp indicator rather than a pest problem.

What the Evidence Says About How Long It Has Been Going On

Useful because cockroach populations grow quickly, and knowing roughly where you are changes how urgently to act.

The bottom three rows are the ones that should change your timetable rather than your reading. None of them is a disaster, and all of them mean the job is larger than it would have been a month earlier.