Which spiders live in east-side Indianapolis basements?
The usual basement spiders on the east side are long-bodied cellar spiders, common house spiders and, close to the floor, wolf spiders. None of them is a danger to people in normal circumstances. Old limestone and brick foundations stay damp and full of small insects, which is why these spiders settle there rather than upstairs.
Cellar spiders are the thin, long-legged ones that hang in loose webs and shake them when touched. Common house spiders build the tangled cobwebs behind the furnace and along the joists. Wolf spiders spin no webs at all; they hunt on the floor, which is why they are the ones that startle people in a laundry room.
Homes near Pleasant Run or a wooded lot sometimes get a dark fishing spider in the basement. It is big enough to be alarming, but it is shy and not aggressive. Purdue Extension's spider publication (E-72) has clear photos if you want to check what you found before you call.
Are brown recluse spiders common in Indianapolis?
No. Purdue Extension says the brown recluse can be found in almost any county in the southern half of Indiana and becomes less common moving north. Indianapolis sits in central Indiana, so the brown spiders people find in local houses almost always turn out to be wolf, house or cellar spiders.
If you think you have one, trap it in a jar or keep a sharp photo for the technician. A recluse has six eyes arranged in pairs and a dark violin shape on its back, while most look-alikes have eight eyes. Purdue's Plant & Pest Diagnostic Laboratory also identifies samples.
Black widows do occur in Indiana, but bites are rare. They like undisturbed outdoor spots such as the underside of deck boards, window wells, meter boxes and firewood stacked against a garage. Wear gloves when you move firewood or clean leaves out of a window well.
Why do more spiders come indoors once fall arrives?
Fall brings two changes at once. Male house spiders and wolf spiders often roam in late summer and early fall looking for mates, and the first cold snaps of September and October push ground-dwelling spiders toward warm foundations. Gaps under doors and around old basement windows let them walk straight in.
The timing lines up with the other fall arrivals. The same weeks that bring boxelder bugs to sunny walls and mice to foundation gaps bring spiders indoors, partly because they follow those insects. A visit that clears webs and treats the foundation line before November usually means a quieter winter.
Spring is the second wave. Egg sacs left in basements and garages hatch as the weather warms, and orb weavers rebuild on porches by midsummer. The Indianapolis pest calendar shows how spiders line up with the rest of the year.
How long does a spider treatment hold up on an older house?
Inside a dry, closed-up basement, a spider treatment usually holds for months. Outside, rain, sun and new spiders from the yard wear it down faster, especially through a wet spring and a humid summer. That is why houses with big porches, mature trees or creek frontage tend to do better with quarterly visits than with one spray.
Old houses also offer more hiding places than new ones: cracks in plaster, loose basement window frames, unfinished attics and porch ceilings with beadboard seams. Each can hold webs and egg sacs that a single visit may not reach, and a follow-up catches what hatches later.
You can stretch any treatment. Keep the basement dry, move cardboard boxes into lidded plastic bins, pull mulch a few inches back from the foundation and switch porch lights to yellow bulbs that draw fewer insects.
How should I get ready for the technician?
Clear access to the basement walls, window wells, sump area and porch ceiling, and pull stored boxes a foot away from foundation walls where you can. Leave the webs up so the technician can see where spiders are active. Mention pets, an aquarium, a vegetable garden or anyone at home who is pregnant or has asthma.
In a historic house, point out anything delicate as well: original woodwork, stained glass, a painted porch ceiling or old plaster that should not be scrubbed. Web removal can be done gently, and treatment can stay in cracks and corners instead of on open surfaces.