The hobo spider question, settled
For years the hobo spider carried a reputation in the Northwest that it did not earn. Early reports linked it to necrotic wounds, the story spread, and people in Montana started treating a common funnel weaver as an emergency. Later work, including research at Utah State University, did not support that link. Current extension guidance across the region no longer treats the hobo spider as medically significant, which means the large brown funnel weaver in your window well is a nuisance rather than a hazard. This matters practically, not just academically. If you believe a dangerous spider is loose in the house, you buy products you do not need, spray rooms that do not need it, and stay anxious about a basement you should be able to use. Knowing the hobo spider is ordinary lets you handle it the ordinary way: vacuum the web, fit a door sweep, and get on with your day. It also frees up attention for the things that actually reduce spider numbers in Montana, which are moisture, clutter, and the gaps that open every winter.
How a dry Montana climate changes spider behavior
About 14 inches of rain a year and median humidity near 59 percent make Montana a harder place to be a small animal that dries out easily. That single fact shapes most of what you see indoors. Insects concentrate where water is: irrigated lawns, creek bottoms, leaking hose bibs, and damp basement corners. Spiders follow them there. A basement or crawl space that holds a little humidity becomes the best real estate on the property, which is why webbing shows up in the same corner every year. It also explains the bathtub problem. A spider that wandered in looking for moisture finds a tub or sink, cannot climb back out of the smooth surface, and is still sitting there in the morning. That spider is not nesting in your drain; it is stranded. The useful response follows directly. Fix the dripping outdoor tap. Run a dehumidifier in the damp corner rather than treating it. Keep gutters draining away from the foundation. Take away the water and you take away the insects, and the spiders leave with their food.
The fall wander, month by month
April and May bring the first outdoor activity as the ground warms and spiderlings disperse. Nothing much happens indoors yet. June through August is the growth season. Median highs near 85F and long daylight produce a short, intense insect season, and spiders eat well. Webs in window wells, under eaves, and along foundation cracks reach full size during these weeks. This is the best stretch to knock them down and to seal what needs sealing. Late August through early October is when Montana households actually notice spiders. Males reach maturity, abandon their webs, and travel looking for mates. That is why you find a big wolf spider crossing the living room floor in September when you saw nothing all summer. It is behavior, not invasion, and the count outside your walls has not changed. From November through March, with lows near a median 13F, outdoor activity effectively stops. Anything moving indoors during a Butte or Great Falls winter has been living in the basement or crawl space the whole time, which makes cold-weather sightings worth tracing to a source.
Shops, barns, and detached garages
Montana properties tend to have more outbuildings than housing in denser states, and that changes where spider work should focus. A shop or barn offers high rafters, still air, no disturbance for months at a time, and doors that stand open through the working season. Webbing accumulates fast, and egg sacs tucked into rafter corners overwinter comfortably. When people say spiders keep coming back after treating the house, the outbuilding is usually the reason. The practical approach is seasonal rather than chemical. Clear rafter webbing with a long-handled brush in late spring and again in early fall. Get stored goods off the floor and into sealed bins so there is less harborage at working height. Fit a bottom seal on the overhead door, which is often the biggest opening on the property. If you do hire someone, ask directly whether the shop is inside the quoted scope. Many quotes cover the house only, and the price difference is worth knowing before the truck arrives rather than after.
Reading a Montana quote
Start with what the number covers. Is identification included, or only application? Does it include web and egg sac removal, or is that extra? Are outbuildings in or out? Is any sealing work part of the price, and if so, which openings? Then ask about method. For spiders, placement into cracks, crevices, and voids does more than spraying open walls and floors, because spiders rest in tight spaces and rarely cross broad treated surfaces. A company leading with fogging is offering volume rather than results. Ask about timing. Given that Montana's indoor sightings cluster in the six weeks after mid-August, a visit scheduled for June may miss the point. Find out when they would come and why. Ask about drive charges, which are a real factor outside Billings and Missoula, and about what triggers a free return visit. Finally, confirm the license is current and get everything above written down. Two quotes only become comparable once both describe the same work in the same words.