Cockroaches

The small pale insect in the kitchen and the large black one in the basement are not the same animal, even though both get called a cockroach. They live in different places, breed at very different rates and need different work to clear. Identifying which one you have is the first job, because a treatment aimed at the wrong species tends to achieve very little.

Telling the two apart

The German cockroach (Blattella germanica) is 13–16 mm long and tan to light brown. Its identifying mark is a pair of dark parallel stripes on the pronotum, running from the back of the head towards the wings. Its flattened body lets it get into very narrow spaces, and it forages mainly at night.

The Oriental cockroach (Blatta orientalis) is far bigger — around 25 mm — and very dark brown to nearly black, with a greasy sheen. The female has only rudimentary wing pads; the male’s wings cover about three-quarters of the abdomen.

They also reproduce at different rates. A female German cockroach produces four to eight egg capsules in her lifetime, each holding up to 48 eggs. That is why a kitchen where two or three insects have been seen can become a great deal busier in a short time.

Where they harbour

German cockroaches choose cracks and crevices that are warm and humid: behind and beneath kitchen units, around fridge and dishwasher motors, in pipe penetrations and in the joints of bathroom cabinets.

Oriental cockroaches want the opposite — dark, damp and cool. Under sinks and washing machines, in damp basements, in drains, sewers and crawl spaces. In dry weather they move indoors looking for humidity, so with this species the source is often not the flat itself but the drainage and the basement below it. It is also why treating one flat in a block usually falls short: the shared areas and the basement have to be dealt with at the same time.

What it means for health

Cockroaches can carry bacteria and viruses associated with gastroenteritis — food poisoning, dysentery and diarrhoea. Their droppings and cast skins also contain allergens, which can trigger skin rashes, watery eyes, sneezing, nasal congestion and asthma symptoms. If anyone in the household has asthma or an allergy, that side of it is a matter for their doctor.

How the treatment works

We start by putting sticky traps in as monitors. They tell us which species is present, where the numbers are concentrated, and afterwards whether the catch is actually falling.

On the same visit we look at where the damp is coming from and which openings the insects are using to move around. A treatment carried out while a pipe is leaking or a service penetration is left open comes back through that same point soon enough.

The treatment itself is bait and crack-and-crevice work rather than blanket spraying. For German cockroaches, gel bait goes down as small placements in the runs and joints the insects actually use. For Oriental cockroaches the weight of the work shifts to drains, basements and voids, supported where appropriate by dust formulations and bait stations. Proofing matters as much as the products: gaps around pipework, door frames and cracks need sealing, or nothing holds.

The products we use are biocidal products licensed by the Turkish Ministry of Health. Fogging over a wide area is considered only where targeted methods cannot reach the problem.

What you can do

• Keep open food in sealed containers and clear crumbs, grease and spills from worktops.
• Take the rubbish out each evening and keep the bin lidded.
• Repair the dripping trap or tap under the sink — cut the damp off at source.

Spraying an aerosol at the insects you can see usually makes the job harder. It drives them deeper into the voids and puts them off taking bait afterwards.