Kelso, Washington · Family-owned since 1963
Kelso Pest Control & Exterminator Services
You want spring and fall to be the nice seasons again. No boxelder bugs stacked up on the siding in March, no ant line to the sink in April, no mouse in the garage when the Cowlitz is running high. Our home office is here in Kelso, and our technicians treat the pests Cowlitz County homes get on a year-round schedule, coming back as part of your plan if they return between visits.
- Plans from $39/mo plus a one-time setup fee
- Re-services included as needed between scheduled visits
- QualityPro certified, licensed in Washington
Request a Free Quote
You can also call us at 360-515-3882 or Book Instantly Here
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Same-day callback Monday to Friday for requests sent before 4pm.
What are you dealing with?
Pick the pest to see what it looks like, why it shows up in Kelso homes and how our team handles it.
Boxelder bugs
Red-and-black bugs on sunny walls in March and again in October, and inside window frames.
On 13% of first visitsBoxelder bug guide →Ants
Odorous house ants at the sink and carpenter ants in damp wood, mostly March through June.
Peak calls: AprilAnt guide →Rats & mice
Norway rats along foundations and under woodpiles, roof rats in attics, deer mice in sheds.
Calls every monthRodent control →Spiders
Webs on the eaves all summer, and giant house spiders indoors as fall starts.
Peak calls: OctoberSpider guide →Also in Kelso: stink bugs, termites, bed bugs, cockroaches and fleas.
Why Kelso homes see the pests they do
HistoryLink, Washington’s online encyclopedia, says Kelso grew between the Cowlitz and Coweeman rivers after Peter Crawford, a surveyor born near Kelso, Scotland, filed the first land claim in Cowlitz County in 1847. The National Weather Service gauge for the Cowlitz River at Kelso lists a record crest of 29.5 feet on February 9, 1996.
NOAA’s 1991 to 2020 climate normals for nearby Longview put rain at 48.12 inches a year, with November, December and January the wettest months and July and August the driest. Wet winters and river-bottom ground mean crawl spaces that stay damp, and that is where rodents and moisture-loving insects settle in.
Some years it feels like a different pest every season: boxelder bugs on the siding, then ants at the sink, then wasps at the barbecue, then something in the walls when the rain comes back.
With a plan, the calendar is ours to watch. Your technician treats ahead of each pest’s season, and if something gets through between visits, one call brings us back, included in your plan.
Common Kelso pest problems and what we do about them
These are the calls our Kelso office takes most. Each one starts with an inspection, because the right fix depends on what is actually there.
When boxelder bugs cover the south side of the house
Interstate Pest Management records for new customers with Kelso billing addresses over the last five years put boxelder bugs on 13% of first visits, about twice the Longview share. The calls come in two waves: March, when the bugs that wintered in walls and attics come back out, and October, when they look for a way in. Sealing gaps and treating the walls where they gather, ahead of each wave, cuts the numbers down.
Boxelder bug guide →When ants show up in the kitchen in spring
WSU says carpenter ant mating swarms generally occur from April to early June, and that many home infestations are satellite nests fed by a parent nest outdoors. In our Kelso records, April brought 19% of the year’s new ant calls, the most of any month. We identify the ant first, because odorous house ants and carpenter ants need different treatments.
Ant guide →When rats move in under the house
OSU says Norway rats burrow along foundations and under woodpiles and adapt to crawl spaces. Kelso sits between the Cowlitz and Coweeman rivers, and a crawl space near the water is where we look first. We inspect, set traps and locked bait stations, and quote sealing for the gaps we find.
Rodent control →When yellow jackets nest in the yard
WSU says ground-nesting yellow jackets also build nests in wall voids or attics and can chew through into a room. The PNW Insect Management Handbook says nests are most troublesome in August and September. In our Kelso records, August brought 20% of the year’s new wasp and yellow jacket calls.
Wasp guide →When deer mice get into the shed or the shop
The Washington State Department of Health says deer mice live throughout the state and carry hantavirus. DOH advises airing a space out and soaking droppings in a bleach solution rather than sweeping them up, and calling a professional for a heavy infestation.
Rodent control →When you need a termite or WDO inspection
Buying or selling a home in Cowlitz County usually means a wood-destroying organism inspection. We inspect for termites, carpenter ants and other wood-destroying insects, write up what we find and quote any treatment after the inspection.
Termite and WDO inspections →
Your Kelso team
Kelso is home base. Interstate Pest Management has been family-owned since 1963, and Mel Thorstenson opened our Kelso branch in 1967. Three generations later, our office on Elm Place still runs the routes that cover Cowlitz County, Wahkiakum County and the Oregon towns across the river.
Our customers give us a 4.96 average across 8,394 Google reviews. We’re QualityPro certified and licensed by the Washington State Department of Agriculture, and our service records for Kelso go back years, so your visits are timed ahead of each pest instead of behind it.
Our re-service promise
If pests come back between your scheduled visits, so do we, and the visit is included in your plan.
Pest Control Pricing in Kelso
Every plan has one monthly price and a one-time setup fee for the first treatment. If pests come back between scheduled visits, so do we, and the visit is included in your plan.
All Seasons Pest Service
$39/mo
$260 one-time setup fee
Year-round coverage for the insects Kelso homes see most, including ants, spiders, wasps and boxelder bugs.
See the Pest planAll Seasons Pest & Rodent Service
$47/mo
$280 one-time setup fee
Everything in the Pest plan plus rats and mice, on one bill.
See the Pest & Rodent planAll Seasons Rodent Service
$39/mo
$280 one-time setup fee
Ongoing rat and mouse control for homes that need rodent coverage only.
See the Rodent planOne-time Rodent Service: no plan, $350 for the first visit, then $60 per follow-up.
Exclusion work is quoted separately and carries a 1-year warranty on materials.
How Kelso service works, in 3 steps
- 1
Book online or call
Tell us what you’re seeing and where. Our Kelso office sets up your first visit.
- 2
Inspection and first treatment
Your technician walks the foundation, siding, eaves, crawl space and garage, finds where pests get in and what draws them, treats the problem and shows you what was done.
- 3
Scheduled visits, re-services included as needed
Visits follow the Kelso pest calendar below, landing before each pest’s busy months. Anything that shows up in between gets a return visit included in your plan.
Local Context: Kelso and Cowlitz County
Kelso gets boxelder bugs twice a year: March and October.
Interstate Pest Management records for new customers with Kelso billing addresses over the last five years show two boxelder bug seasons. March brought 33% of the year’s new boxelder bug calls and October brought 26%, with almost nothing in the summer between. Boxelder bugs were on 13% of first visits for new Kelso customers, compared with 6% next door in Longview.
Few people here post them online. iNaturalist, where people photograph insects and others confirm the ID, shows only 63 verifiable boxelder bug sightings across Cowlitz, Wahkiakum, Columbia and Clatsop counties over the same five years. For a bug that shows up on 13% of our new Kelso customers’ first visits, that tells you Kelso homeowners pick up the phone instead of the camera.
The rest of the year follows its own pattern. Ant calls in Kelso peak in April at 19%, wasp and yellow jacket calls peak in August, and spider calls run from June into October. Rats and mice show up in every month, with no single month above 10% of the year.
Be ready before March. Start a plan now and your visits land ahead of the spring boxelder and ant surge, with re-services included as needed between visits.
Book NowShare of each pest’s first-time calls by month. Source: Interstate Pest Management service records, first appointments of new customers with Kelso billing addresses over the last five years. Each row sums to about 100%.
Mosquitoes, invasive moths and other things the county watches
Cowlitz County has its own mosquito control district, formed in 1990, with board seats for Kelso, Longview, Kalama, Castle Rock and Woodland. The district runs its treatment season from about February through August and takes calls at 360-423-5311. The Washington State Department of Health’s West Nile virus data shows no detections in Cowlitz County in 2026.
The Washington State Department of Agriculture treated a site at Silver Lake in Cowlitz County for spongy moth in 2021. Emerald ash borer, a beetle that kills ash trees, was confirmed in Vancouver in August 2026 and has not been reported in Cowlitz County. Both are tree pests, and we don’t treat trees.
| Insect or spider | Sightings |
|---|---|
| Cross orbweavers | 226 |
| Giant house spiders | 109 |
| Carpenter ants | 87 |
| Boxelder bugs | 63 |
| Yellow jackets | 62 |
| Brown marmorated stink bugs | 51 |
What our customers say
4.96 average from 8,394 Google reviews
“Interstate Pest sent Yarrow who showed up on time and thoroughly sprayed our house to combat the Box Elder Beetles which have been coming on strong this year. He shared his expertise and addressed our many concerns as this was our very first pest treatment ever.”
“These guys are awesome! They have handled everything from mice to ants, wasps and a huge yellow jacket nest inside the wall next to my front door. Don’t hesitate to call if you have anything that needs to be eliminated. They have competitve prices per job, as well as affordable monthly plans available. They are very responsive and great with communication. All of the guys who have come out are, professional, knowledgeable and friendly.”
“Jared is amazing! I recently purchased a 100 year old home and inherited ants, bees, and rodents. It’s taken several iterations but Jared eradicated everything. Very professional and affordable. Interstate pest management has been a game changer.”
Serving Kelso, Longview and the lower Columbia
Same team, same plans and same re-service promise across Kelso, West Kelso and the hills above town, and out to every town our Kelso office covers. On the Washington side that means Longview, Castle Rock, Kalama, Woodland and Cathlamet. Across the river in Oregon it means Rainier, Clatskanie, St. Helens and Scappoose, and out to Astoria, Seaside and Cannon Beach on the coast.
Kelso pest control questions
Still deciding? Our Kelso office answers the phone Monday to Friday, 8am to 5pm.
How much does pest control cost in Kelso?
The All Seasons Pest Service is $39/mo with a $260 one-time setup fee. The All Seasons Rodent Service is $39/mo with a $280 setup fee, and the All Seasons Pest & Rodent Service is $47/mo with a $280 setup fee. The One-time Rodent Service is $350 for the first visit, then $60 per follow-up. Exclusion work is quoted separately.
When is pest season in Kelso?
It changes through the year. In Interstate Pest Management records for new Kelso customers over the last five years, boxelder bug calls peaked in March and October, ant calls in April, wasp and yellow jacket calls in August and spider calls in October. Rodent calls came in every month.
Why do boxelder bugs keep coming back every fall?
They look for a dry place to spend the winter, often inside walls and attics on the sunny side of the house, and come back out in spring. They don’t breed indoors. Sealing gaps around windows, siding and vents before October keeps most of them out, and our plan covers treating the walls where they gather.
Does Cowlitz County handle rats?
Cowlitz County Health has a zoonotic disease program for animal-to-human disease but does not describe a rodent service. For rats in the crawl space or attic, call us.
Who handles mosquitoes in Kelso?
The Cowlitz County Mosquito Control District treats mosquitoes across the county from about February through August and takes calls at 360-423-5311. Mosquitoes are a rare request for us.
What if pests come back between visits?
Call us. Re-service between scheduled visits is included on every All Seasons plan.
How fast will someone get back to me?
Quote requests sent before 4pm, Monday to Friday, get a call back from our Kelso office the same day.
Is there anything you don’t treat?
Ticks, moles, voles, wildlife and tree pests like spongy moth and emerald ash borer are outside what we do. Call anyway and we’ll suggest where to start.
Call our Kelso office
Interstate Pest Management
1301 Elm Pl
Kelso, WA 98626
Monday to Friday, 8am to 5pm
Washington State Department of Agriculture License #229
Take the fast lane to a pest-free home.
Picture a March without boxelder bugs on the siding, an April without ants at the sink and a winter with a quiet crawl space. One call sets up the whole year, with plans from $39/mo plus a one-time setup fee.