How Do Pest Control Companies Get Rid of Cockroaches?

People often picture pest control as someone in a mask fogging a room. For cockroaches that picture is mostly wrong. The work is quieter and more precise than that, and the reasons behind each step explain why supermarket products so rarely finish the job.

Step One: Work Out Where They Really Are

A cockroach seen on a worktop at midnight is a forager. The colony it came from is somewhere warm, dark and tight: a motor housing, the void under a plinth, a gap around a waste pipe. Treating where the insect was spotted misses almost everything.

So the first visit is detective work. A technician uses a torch, looks for droppings and cast skins, checks the smell in enclosed spaces, and opens up the places householders never see. Often they set sticky monitoring traps in a few positions. Traps catch very little on their own, but where they catch the most tells you where the centre of the problem is.

Step Two: The Tools That Reach Hidden Colonies

Gel bait

Small spots of insecticidal gel are placed in cracks and crevices close to where cockroaches are living. They feed on it and go back to shelter. Other cockroaches then pick up the insecticide from droppings and dead bodies, so the effect spreads well beyond the insects that fed directly.

Dusts in voids

Fine insecticidal dust puffed into wall voids, behind panels and under units coats the surfaces cockroaches walk through. It stays active in dry, enclosed spaces where a liquid would not reach.

Targeted residual treatment

Where a residual insecticide is used, it goes on the specific surfaces around harbourages, not across open floors and worktops. Food-contact areas are kept out of it.

Growth regulators

Some programmes add an insect growth regulator, which interferes with young cockroaches maturing and breeding. It does not kill adults quickly, but it stops the next generation replacing them.

Why Sprays From the Shop Fall Short

An aerosol kills what it touches and repels the rest. The survivors retreat further into the building and, in flats and terraces, sometimes into the property next door. The repellent film left behind can also put cockroaches off gel bait, which is the tool most likely to work. That is why we ask whether you have sprayed before we treat.

Foggers and bug bombs have the same weakness on a larger scale. The mist settles on open surfaces, which is exactly where cockroaches are not.

Killing the cockroaches you can see is the easy part. The ones you cannot see are the infestation.

Step Three: Follow-Up and Timescale

Cockroach eggs are protected inside a hard case, and many treatments do not affect them. Young cockroaches keep hatching after the first visit, which is why seeing a few in the following week or two is normal. Baits and dusts keep working on those hatchlings as they emerge.

For an established problem, a follow-up visit is usually part of the plan. At that visit the technician checks the monitors, tops up bait where it has been eaten and looks for any area that was missed. We tell you before you book whether a follow-up is likely and what it involves, rather than surprising you with it.

Every treatment is guaranteed, and the terms are simple: if the problem comes back within 14 days of treatment, we return and re-treat free of charge.

What the Householder Does

The professional side only works if the environment stops helping the cockroaches.

• Give clear access to the areas behind and under appliances before the visit
• Do not clean away gel bait spots or wipe down treated voids
• Stop leaving food and water out overnight, including pet bowls
• Get rid of stored cardboard, which they shelter in and which can bring more in
• Report where you still see them, and when, so the follow-up is aimed properly

For our price and what it includes, see the cockroach control cost guide. For the Cambridge service in plain terms, read cockroach control in Cambridge, and for premises that handle food, cockroach control for your business. Cockroaches often come up in any list of the most stubborn pests; our post on the hardest pest to get rid of explains why. If you want to compare with other pests, the full price list is published.