Field plate · Parasteatoda, Pholcus, Steatoda & others
Common spiders of NW PA houses
Cobweb spiders in the corners, cellar spiders on the basement ceiling, and the occasional bold jumping spider on the sill. Mostly free pest control.
Plate 22 of 28. Drawn in profile to the identification marks named below; the scale rule is a drawing convention — sizes are given in the text.
Identification marks
The tenants you will actually meet: common house spider (4–6 mm, tan with a bulbous patterned abdomen, tangled cobweb in a window corner); cellar spider (fragile, very long legs, hangs upside-down in a loose basement web); sac and jumping spiders, which hunt without webs.
Look-alikes it is confused with
The feared look-alikes deserve a calm word: black widow spiders are rare and localised in Pennsylvania and brown recluse are not established in Erie County — a 'recluse' diagnosis from a photograph of a common spider is almost always wrong, and a skin lesion is a matter for a clinician, not a pest guess.
Where it hides in a house
Quiet, undisturbed geometry: window and ceiling corners, basement joists, behind furniture, in closets and garages. Cobwebs accumulate where flying prey travels and nobody dusts.
Health & property risk, stated plainly
Low. House spiders bite only when trapped against skin, and common species are not considered medically significant. Their webs, however, are honest indicators of the insects entering the house — read them as monitoring data.
What actually works
A vacuum and a duster, done regularly, is the whole program for most houses: remove webs, seal the window gaps the prey uses, reduce the night lighting at doors that draws prey in, and relocate the bold ones outdoors with a cup and card if you like.
What doesn't
A standing pesticide contract for spiders alone — treatments kill the spider and not the prey population or the gaps, so the corner refills in a fortnight.
When to call a licensed pro
Call a pro when webs point to a real prey infestation (cluster flies, pantry moths), or when a genuinely unusual spider needs an in-hand identification. Photograph it beside a coin for scale; do not handle it.