Most of a routine treatment goes outside: along the foundation, up to three feet on the wall, and around doors, windows and vents. Inside, a technician treats the cracks where insects live, under baseboards, around plumbing and behind appliances, not floors, counters or furniture.
Several of the pests people call about most are never sprayed. Mice and rats get traps, bait stations and sealed gaps. German cockroaches and many ants get bait. Termites get a soil treatment or bait stations. And nothing goes on a mattress unless the product is labeled for it.
The Inspection Comes Before the Sprayer
People picture a technician walking in with a tank and misting the rooms. A good visit starts the other way round: finding out what the pest is and where it lives, because that decides whether anything gets sprayed at all.
That means looking where insects leave evidence. Droppings and shed skins under the sink and behind the fridge. Mud tubes on the foundation. Gnaw marks and grease smudges along the garage wall. Webs in the corners of window frames. Soft wood around a leaking pipe. The pest and the evidence together tell the technician which of four tools the job needs: a liquid, a bait, a dust, or a trap and some sealant.
What Gets Sprayed, and What Gets Something Else
| Pest | Where a technician works | What's used | Sprayed? |
|---|---|---|---|
| Ants coming in from outside | Foundation, entry points, trails | Exterior liquid band, bait indoors | Outside, yes. Inside, mostly bait |
| German cockroaches | Kitchen and bathroom cracks, appliance voids | Gel bait, dust, growth regulator | Rarely. Spray drives them off the bait |
| Palmetto bugs (American cockroaches) | Foundation, crawl space, garage, drains | Exterior liquid, granular bait, dust | Outside and in voids |
| Spiders | Eaves, window frames, foundation | Web removal, exterior spot treatment | Spot treatment only |
| Mice and rats | Entry gaps, runways along walls, attic | Snap traps, tamper-resistant bait stations, sealing | No |
| Subterranean termites | Soil around and under the house | Liquid termiticide in a trench, or bait stations | Into the soil, not the rooms |
| Bed bugs | Bed frame joints, furniture seams, baseboards | Heat, labeled products, encasements | Only with a product labeled for it |
| Fleas | Where pets rest, carpet, yard | Labeled carpet treatment with growth regulator, yard treatment | Yes, where the pet sleeps |
Outside: Where Most of the Product Goes
The exterior treatment does the heavy lifting. Most crawling insects that end up in a house walked in from the yard, so the aim is to meet them at the foundation before they find a gap.
The University of Kentucky's extension entomologists describe the standard perimeter as a band two to six feet wide along the ground and two to three feet up the foundation wall. They add the base of every exterior door, the garage and crawl space entrances, foundation vents, utility openings, and up underneath the siding.
That height isn't arbitrary. Since 2009, the EPA has required labels on pyrethroid products, the chemistry behind most professional perimeter sprays, to limit outdoor use to spot or crack-and-crevice treatments only, with three exceptions: soil and plants around the house, lawns, and building foundations "up to a maximum height of 3 feet." Sidewalks, driveways, patios, porches, windows, doors and eaves get spot or crack-and-crevice treatment only. The rule exists because product sprayed on hard surfaces washes into storm drains and creeks, and the same labels say not to apply during rain.
So if your patio is poured right up against the back wall, the technician can't lay a three-foot band across it. They treat the joint where the slab meets the foundation, the gaps around the door, and the soil at the edges. If you ever watch someone spraying a whole driveway or wetting the siding up to the roofline, that isn't thoroughness. It's off-label.
What else happens outside, and matters as much as the spray:
- Webs and wasp starts come down from the eaves and window corners.
- Mulch and pine straw get pulled back from the foundation. A thick layer against the wall keeps the soil damp and gives insects a covered path to the siding.
- Gaps get pointed out: a missing crawl space vent screen, the space around an AC line, a door sweep that no longer touches the threshold.
- The crawl space gets treated, if you have one. It's where palmetto bugs and spiders spend the day.
Inside: Cracks, Not Floors
Indoors the rule is crack and crevice. Insects travel along edges and rest in gaps, so a technician puts a small amount of product into the gap and very little in the open where you live.
The places that get treated are the joins: where the baseboard meets the floor, where plumbing comes through the wall under the kitchen and bathroom sinks, the void behind the dishwasher and under the stove, the hinge side of cabinets, and the frames of exterior doors and windows. Our guide to spraying bug spray indoors walks through the same principle room by room for anyone treating their own home.
| Room | Treated on a routine visit? | Where, if so |
|---|---|---|
| Kitchen | Yes | Under the sink around pipes, behind the fridge, stove and dishwasher, cabinet hinges. Bait for roaches and ants. Never counters or food shelves |
| Bathrooms | Yes | Around pipes under the sink and behind the toilet, gaps at the tub edge, baseboard cracks |
| Laundry and utility | Yes | Where the washer, dryer and water heater lines come through the wall |
| Garage | Yes | Slab edges, the garage door frame, wall penetrations, and the door into the house |
| Living room | Usually no | Baseboard gaps and exterior door frames only if there is activity there |
| Bedrooms | Not routinely | Only for a specific problem such as fleas or bed bugs, and then with products labeled for it |
| Attic | Inspected, rarely sprayed | Traps and bait stations for rodents; dust in voids for some insects |
| Crawl space or basement | Yes | Foundation walls, sill plate, pipe and vent openings |
What a professional doesn't do is spray countertops, the inside of cabinets where dishes and food sit, open carpet, upholstery or bedding. Food-contact surfaces are off-limits on the label, and a wet floor puts the product where you and your pets walk instead of where the insects hide.
Wall voids get dust, not spray
The empty space inside a wall is where German cockroaches, ants and silverfish often live, and liquid doesn't reach it well. A technician uses a hand duster to puff a very fine layer of insecticidal dust, often boric acid, through existing openings: gaps around pipes under the sink, the edges of switch plates and outlets with the power off, and weep holes in brick. University of Florida entomologists recommend a deposit barely visible to the naked eye. Boric acid keeps working almost indefinitely as long as it stays dry, and the inside of a wall is about as dry and undisturbed as a house gets.
German cockroaches get bait, not spray
If the problem is small brown cockroaches in the kitchen, expect tiny dots of gel bait inside cabinet hinges and behind appliances, not a spray. Sprays repel German cockroaches, and anything sprayed near bait makes them avoid it. In NC State field trials, gel baits cut German cockroach populations by 70 to 93% within a month, in the same apartments where store-bought foggers barely dented them. A technician may add an insect growth regulator, which stops nymphs from maturing into breeding adults. Our cockroach control page covers how a treatment plan runs.
What Doesn't Get Sprayed at All
Mice and rats. No spray controls rodents. Control means snap traps along the walls where they run, bait in tamper-resistant stations that children and pets can't open, and sealing the gaps they use. Cornell's integrated pest management program puts exclusion first: seal the openings that let rodents in or move from room to room. If the old advice to spray the attic for rats sounds familiar, it's simply wrong. Rodent control is traps, stations and sealing.
Termites. Termites aren't treated by spraying rooms or wood. Clemson's Home & Garden Information Center describes the two professional methods. One is a liquid termiticide in the soil under and around the house, where trenching around the structure and drilling into the slab are needed to make a continuous barrier. The other is bait stations in the ground, usually every 10 to 20 feet around the building, which leave no residue in the soil but can reduce and even eliminate a colony. Either way the treatment goes into the ground. The options are laid out on our termite control page.
Bed bugs in the bed. The EPA lists applying a pesticide to a bed, furniture or clothing that isn't on the label as an illegal practice. Professional bed bug work relies on heat, mattress encasements, and products labeled for the specific surfaces they're used on, applied to bed frame joints, furniture seams and baseboard gaps rather than the sleeping surface. It also needs a follow-up visit, which the EPA says to insist on. Our bed bug treatment page explains what's involved.
What You'll See on the Day
Most of the visit happens outside. Inside, a technician will usually ask you to clear under the kitchen and bathroom sinks and pull a few things back from the baseboards. If you're treating for cockroaches, our preparation checklist lists what to move.
For most interior crack-and-crevice work you don't need to leave. The label sets the re-entry time, and for most general pest products it's until the treated areas are dry. Keep children and pets out of treated rooms until then. The details, including what signal words like "Caution" mean, are in our guides to whether you have to leave the house and whether pest control is safe for children and pets.
Why You Might See More Bugs Afterward
Seeing insects for a week or two after a treatment is common, and it usually means the treatment is working. Insects flushed out of the walls cross treated areas on their way out, and baits take days to move through a colony because the delay is how they reach the nest. If activity is still climbing after two weeks, that's worth a call. We go through what's normal and what isn't in still seeing bugs after pest control.
Sources: University of Kentucky Entomology, How to Pest-Proof Your Home (EF641); EPA pyrethroid outdoor labeling requirements (2009); Clemson HGIC 2447, Subterranean Termite Control; Cornell CALS IPM, Managing Mice and Rats; University of Florida ENY-258, Least Toxic Methods of Cockroach Control; DeVries et al., J. Econ. Entomol. 112(5), 2019.
Frequently Asked Questions
Usually a little, into cracks and gaps rather than across rooms. Most of a routine treatment goes on the outside, and for several common pests the indoor work is bait, dust or traps rather than spray.
Not on a routine visit, unless there's a specific reason such as fleas where a pet sleeps or bed bugs. Even then, beds and bedding are only treated with products labeled for them, and most of the work goes into frame joints and baseboard gaps.
No. Food-contact surfaces and the areas where dishes and food sit are off-limits on the label. Kitchen work goes into the gaps under the sink, behind appliances and along cabinet hinges, often with bait instead of spray.
Up to three feet on the foundation, under the EPA's labeling rules for pyrethroid products, plus spot treatments around doors, windows, eaves and vents. Spraying the whole wall or the driveway is off-label.
No. Rodents are controlled with snap traps, tamper-resistant bait stations and sealing their entry points. No spray controls them.
The label sets it. For most general pest products it's once the treated areas are dry. Keep children and pets out until then.