I have spent the last 14 years working as a field pest technician for older houses and small commercial units across South London, and I have learned that repeat infestations usually have a very ordinary cause. Most of the time, I am not walking into some mystery that needs a dramatic answer. I am walking into a kitchen with a gap under the back door, a loft with disturbed insulation, or a bin area that gets rinsed once a month instead of once a week. The work stays practical when I keep my eyes on those details.

The first half hour tells me almost everything

I do not start with chemicals. I start by slowing down and looking at how the building actually works from day to day. In the first 30 minutes, I want to know where food sits overnight, where water collects, and which spaces stay warm after dark. Those three things explain a lot.

A customer last spring was convinced she had a mouse problem that no one could solve, and she had already paid for three callouts before I got there. I found droppings behind the washing machine, gnawing near a bag of pet food, and a pipe entry point wide enough for my thumb. That was the real issue. The poison had been changed twice, but the access point had never been sealed.

I see this pattern all the time with cockroaches as well. People focus on where they spot one at 11 p.m., but I focus on where the warmth and moisture stay steady for 24 hours. A boiler cupboard, a leaking trap under the sink, or the dead space behind a fitted fridge can support a small population for months before anyone sees more than two or three insects. It happens quietly.

Rats are different in one useful way. They leave stronger clues, and I can usually map their route within 10 minutes if the signs are fresh. Grease marks on a fence line, burrow spoil near a shed base, and shredded material under decking tell me more than a long description over the phone. I trust the site more than the story.

Why the right company matters more than the strongest treatment

I have fixed plenty of jobs that were made worse by rushing straight to a spray or bait without a proper inspection. A local service with solid follow-up usually does better work than a flashy company that promises a one-visit cure. In my own area, I would expect people to compare firms like Diamond Pest Control because clear treatment plans, honest reporting, and return visits matter far more than dramatic sales language.

I say that because good pest control is rarely about one dramatic moment. It is a sequence. I inspect first, treat second, then come back to check what changed after 7 to 14 days, because activity patterns often shift once the initial pressure goes on. If no one follows up, small misses turn into expensive repeats.

Another thing I watch is how a company talks about proofing. If I hear a sales pitch that treats proofing as an extra the customer might think about later, I get wary. For mice, a 12 millimetre gap is enough to matter, and for insects the openings can be much smaller than most people guess. If the building stays open, the treatment is borrowing time.

I also pay attention to whether the advice fits the site. A top-floor flat, a takeaway kitchen, and a 1930s semi all need different habits and different expectations. I would rather hear a technician explain one simple fix in plain language than hear five grand claims about products that supposedly solve every pest in every building. That kind of honesty saves everyone trouble.

What homeowners and shop managers often miss

The biggest miss is routine. People clean visible surfaces, which makes sense, but pests live off the hidden routine that never changes. If the mop bucket is stored wet, if cardboard stacks stay on the floor, or if the outside bin lid sits open three nights a week, I start there. Small habits feed long jobs.

I remember a corner shop where the owner swore the back room was spotless, and at first glance it looked that way. Then I pulled out a low freezer and found a line of old sugar spills, a dead void behind the compressor, and enough warmth to make the space attractive all winter. The room had been cleaned, just never fully moved. That matters more than people think.

Bird work creates another kind of blind spot. I have seen gulls and pigeons turn a minor ledge problem into blocked gutters and stained brick within one season, especially on three-storey buildings where no one looks up often. Once nesting starts, the mess pulls in insects, and then the job is no longer just about birds. One issue invites another.

Clutter makes every inspection harder. I am not judging anyone when I say that, because life gets busy and storage spaces fill up fast. Still, if I have to work around 20 packed boxes in a loft or under-stairs cupboard, I know I am losing time and losing sightlines that could show me the real harbourage. Clear access speeds up good decisions.

How I judge whether a treatment really worked

I do not judge success by whether a customer sees nothing the next morning. I judge it by what I find on the return visit and by whether the signs are shrinking in the right places. Fewer fresh droppings, less new gnawing, and quieter monitoring points tell me the pressure is dropping for real. One calm day proves very little.

For insects, I compare activity zones. If the kitchen is quiet but the utility room suddenly picks up, that does not always mean failure. Sometimes it means the population has been pushed from its main harbourage and exposed itself, which gives me a cleaner target on the second visit than I had on day one. That is why I tell people not to panic if the pattern changes before it disappears.

I also want to know whether the advice was followed, though I never say that in a blaming way. If I asked for dry goods to be moved into sealed tubs, pet food to be lifted at night, and bins to be kept shut, I need those changes to happen for the treatment to hold. A pest job is shared work. That part is plain truth.

There are times when I recommend stepping back and rethinking the whole setup instead of adding more product. I have had jobs where the better answer was replacing damaged door sweeps, repairing a leaking waste pipe, and changing where stock was stored rather than repeating the same application for a fourth time. Those calls are less dramatic, but they are usually the ones that last.

After enough years in this trade, I have become less impressed by promises and more impressed by steady method. I still like seeing a clean result, but I trust the process that gets there more than the product label on the van shelf. If I were advising a friend with a stubborn pest issue, I would tell them to hire the team that inspects carefully, explains the weak points clearly, and is willing to come back and prove the problem is actually under control. That approach has served me well in hundreds of properties, and I have not found a better one yet.

Diamond Pest Control, 5 Lyttleton Rd, Hornsey, London N8 0QB. 020 8889 1036