Spiders are the number one pest problem in the Treasure Valley, and Boise is not one spider job, it is several. The house tells the story: an old North End foundation, a Bench ranch, and a rental near Boise State each have a different way for spiders to get in and a different reason they stay. This page covers why your part of Boise gets them and how we get rid of them. Rather skip ahead? Call (208) 949-5184.
Why Boise homes get spiders
Boise is a mix of old bones and mixed terrain, and both feed spiders. Start with the housing. The North End and much of the Bench were built when a lot of today's subdivisions were still orchards, and decades of settling have opened pencil-width cracks in foundations, worn out old window seals, and left gaps around sill plates and utility lines. A new build is closed up tight. An old Boise home is not, and every one of those gaps is a spider entrance.
Then there is the food. A spider does not settle where the view is nice, it settles where the hunting is good, and mature irrigated Boise yards are excellent hunting. Old maples and long-established landscaping shelter crickets, moths, and gnats, and the insects a spider hunts gather thickest right where the watering happens. The Boise River and its greenbelt run a corridor of moisture and bugs through the south of the city, so homes near the river tend to carry a heavier prey load, and the spiders track it.
Finally there is the edge. The Boise Foothills sit right above the north side of town, and ground-hunting spiders drift down out of that dry open country toward warm houses when the weather turns. Foothill-adjacent streets get the wanderers. River-corridor homes get the prey base. The old core gets the entry gaps. Different Boise, same result, which is why the fix is tailored to your house rather than sprayed by rote. For the full rundown of which spiders live here, our guide to spiders in Idaho covers all nine.
How we treat spiders in Boise
Spiders are genuinely hard to kill with a can from the hardware store, and there is a real reason for it. They stand high on the tips of their legs, so almost none of the body touches a treated surface, and they do not groom themselves the way ants and roaches do, so they never ingest a dried film. That is why we reach for Onslaught FastCap, a professional microencapsulated product. Instead of drying flat, it leaves millions of tiny capsules that catch on a spider's legs and get carried back to where it hides, which is a completely different way of reaching a spider than an ordinary spray.
Around that, we take down the webs and egg sacs by hand on every visit, because one sac holds dozens to a few hundred eggs and removing it stops the next generation. Then we lay a Bifen barrier around the foundation and lower walls to knock down the crickets and other prey that made your home worth hunting, and we point out the old-foundation gaps worth sealing while we are there. The full method is laid out on our valley-wide spider control page. Since those same old foundations are highways for other pests, a lot of Boise homes fold spiders in with ant control on one plan.
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Get a Free Quote →When Boise spiders peak
The big wave is late August through October. The spiders that hatched in spring reach full size by then, so the ones you have ignored all year suddenly look huge, and the male hobo spiders leave their webs to wander for mates. The first cold nights in the foothills add a second push as ground spiders move toward warmth, so North End edge and Highlands homes notice them earliest. A fall treatment does double duty: it clears the spiders you can see and removes the egg sacs that would otherwise become April's population. You can see how spiders fit the whole pest year on the Treasure Valley pest calendar.
What you can do yourself
We are a pest control company telling you how to need us less. Every item here helps.
- Seal the gaps an old house gives you. Foundation cracks, worn window seals, and the gap under the garage door are the busiest spider entrances on a North End or Bench home. Caulk and fresh weatherstripping go a long way.
- Swap bright porch bulbs for warm yellow LEDs. White light pulls in the night insects spiders eat. Fewer moths at the door means fewer webs around it.
- Knock webs down weekly. A long broom across the eaves and porch corners makes your entry a bad place for a spider to set up.
- Pull firewood and clutter off the foundation. That stack against an old Boise wall is prime black widow real estate. Shake out shoes and gloves stored in the garage too.
- Trim shrubs and old maples back off the siding. Any branch touching the house is a bridge over every barrier you put down.
When to call a pro
If you are seeing spiders in the living space every week, finding widows in the garage, or watching webs rebuild faster than you can sweep them, the population around your home is big enough that treatment will earn its keep. Foothill-edge homes fighting the fall wander and old-core homes with rodents using the same gaps often want the whole perimeter handled at once, which is where a plan that also covers rodents makes sense. Your quote is free, the first service is $50 off, and you get a real number before any work starts. Request a free Boise quote and we will tell you honestly what it takes.
Boise spider questions
Do older Boise homes really get more spiders than new builds?
Often yes, and it comes down to entry points. A North End bungalow or a Bench ranch has had decades to settle, so the foundation, the sill plate, and the old window frames have opened gaps a spider can walk right through. New homes are sealed tighter. Pair that with mature yards full of insect prey and older Boise streets give spiders both a way in and a reason to stay.
I keep finding long-legged spiders in my Boise basement. Should I worry?
Almost certainly not. The thin, dangling spider in an old Boise basement or crawl space is a cellar spider, and it poses zero threat to people or pets. The one to check for in a dark, undisturbed corner is a black widow, glossy black with a red hourglass. If you are not sure what you found, send us a photo and we will tell you which it is.
Do spiders come down out of the Boise Foothills in the fall?
Ground-hunting spiders like wolf spiders do move toward warmth once the nights cool off, so homes along the foothill edges above the North End and in the Highlands see more of them from September on. They do not build webs. They wander in under garage doors and thresholds, which is why sealing those gaps before fall pays off.
Will sealing the cracks in my old foundation actually cut down spiders?
Yes, and on an old Boise home it is one of the highest-value things you can do. Every gap you close is one fewer door for a wandering spider. Sealing alone will not empty a yard that is full of prey, so it works best paired with treatment and web removal, but exclusion is the part that keeps the next one from getting inside.