Pest control starts with identification, not spraying

It depends on whether the pressure is an event or a constant. A wasp nest or a single overwintering flare-up is a one-off, while ants, spiders and outdoor cockroaches pushing in from a wooded or damp lot are continuous, and a single exterior application breaks down over weeks to a few months depending on weather, sunlight and surface. A recurring program is aimed at suppressing that ongoing pressure, not at removing it permanently. It is also not a substitute for exclusion and sanitation — if the schedule is the only thing holding pests back, something structural or environmental has not been fixed.

For subterranean termites the classic evidence is pencil-width mud tubes running up foundation walls, piers or joists, plus hollow-sounding or blistered wood and swarmers or discarded wings near windows, usually in spring though the timing varies by species and region. Drywood termites leave small piles of hard, pellet-like frass beneath tiny kick-out holes instead, and need no soil contact at all. A wood-destroying insect (WDI/WDO) inspection also documents conducive conditions — wood-to-soil contact, buried form boards, leaks, poor crawlspace ventilation — that predict future problems even where nothing is currently active. Because subterranean and drywood infestations call for entirely different treatments, identification has to be settled before any product is chosen.

Ask which product will be applied, exactly where it will be placed, and to see the label and safety data sheet — the label carries the legally binding directions, including any re-entry or drying instructions, and applicators are licensed by the state in most jurisdictions. Pesticides used in structural pest control are EPA-registered, and it is reasonable to ask for the specific placement and re-entry guidance for your situation rather than a general reassurance. Lower-exposure approaches can also be discussed: bait confined inside a tamper-resistant station, crack-and-crevice and void placement rather than open surfaces, and non-chemical steps such as heat, trapping, exclusion and moisture repair. Raise pregnancy, small children, pets, fish tanks, beehives and respiratory conditions before the visit so placement and timing can be planned around them.

Some of it is expected. Bait works by being carried back to the nest, so activity can look unchanged or briefly heavier before it drops, and cockroach and bed bug eggs already laid will hatch after the first visit, which is why follow-ups are scheduled to the hatch cycle rather than to the calendar. Some of it is counterproductive DIY: spraying a repellent product over gel bait placements can stop insects feeding on the bait, and spraying visible trails of certain ant species can cause budding, splitting one colony into several. And some of it means the plan itself was wrong — the wrong species was targeted, or an unsealed gap, a leak or a food source is still supporting the population, which is what the follow-up inspection is for.

Homeowners can do most of the highest-value work: emptying standing water weekly, cleaning gutters, fixing leaks, fitting door sweeps, screening vents and weep holes, moving firewood and mulch off the foundation, decluttering and tightening up kitchen sanitation. Snap traps placed against walls and runways also handle a small mouse problem well. What generally goes badly as DIY is German cockroaches, bed bugs, termites and structural rodent exclusion at height — these need identification, equipment and a repeat schedule, and mistakes are expensive to undo. Rodenticide in particular deserves caution outside a professional program, because a poisoned rodent can be eaten by an owl, hawk, cat or dog, creating a documented secondary poisoning risk that trapping and exclusion avoid entirely.