Cellar spider

How to recognise it

These are the features that identify a cellar spider. Each one is described in words so the identification works without the diagram.

1. Extremely long, thin, fragile legs — up to five or six times the body length — with a small, pale, elongated body.
2. Colour is pale tan to grey, translucent, with a cylindrical abdomen.
3. When disturbed in its web it vibrates rapidly, becoming a blur. This behaviour is characteristic.
4. The web is an irregular, untidy tangle in ceiling corners, not an orb.

What it leaves behind

• Loose tangle webs accumulating in ceiling corners, basements, crawl spaces, and garages.
• Accumulated shed skins and prey remains beneath the web.

Why an infestation persists

Harmless to people and a frequent predator of other spiders, including species of greater concern. Persistent webbing indicates available prey and undisturbed space rather than a problem in itself. The widely repeated claim that they are highly venomous but unable to bite through human skin has no scientific support.

Where it occurs

Throughout the United States, almost entirely indoors and in protected structures.

Where to look for it

• Ceiling corners in basements, garages, porches, and rooms that are rarely disturbed.
• Behind and beneath stored items in a cellar or crawl space.
• Around windows where flying insects gather, since the web follows the prey.
• The underside of stairs and the space behind a boiler.

When you see it, and why

Present year-round indoors with a rise in autumn as insects move inside and the prey supply increases. Webs accumulate rather than being rebuilt, which is why an unused room can look heavily infested after a single season — the quantity of webbing reflects time undisturbed more than the number of spiders.

What getting the identification wrong costs you

Frequently reported as a recluse because both are pale brown and long-legged at a glance. The body shape settles it: a cellar spider has a small cylindrical body with extremely long thin legs and vibrates rapidly when disturbed, which no recluse does. It is also worth naming the myth directly — the claim that daddy long-legs are highly venomous but cannot bite through human skin has no scientific support.

What a professional actually does

Nothing here justifies a service call. The spiders are harmless, the webbing comes down with a vacuum or a broom, and it only rebuilds where there is prey to catch — so reducing exterior lighting near doors and correcting basement damp does more than any treatment would. Persistent heavy webbing is a signal about the insect population and the damp, not about the spiders.