Pholcidae family
Spider
1/4 to 5/16 inch body, 1 to 2 inch legspan
Pale tan or gray
1 to 2 years
About the Cellar Spider
Cellar spiders (also called daddy long-legs or long-bodied cellar spiders) are thin-legged web-building spiders common in Michigan basements, garages, crawlspaces, and dark corners of rooms. Despite the urban myth, cellar spiders are not the world's most venomous spider. They are harmless to humans.
Habits & Behavior
Cellar spiders build loose, tangled webs in dark, undisturbed corners. They hang upside down in their webs waiting for prey (including other spiders). When disturbed, they vibrate rapidly in the web to appear larger. They prefer humid locations with stable temperatures.
Signs of a Cellar Spider Infestation
Thin tangled webs in ceiling corners, behind furniture, in basement rafters
Pale spiders with extremely thin legs hanging upside down in webs
Rapid vibrating motion when disturbed
Accumulations of old webs and shed exoskeletons in undisturbed corners
Cellar Spider Pressure in Michigan
Cellar spider populations are stable year-round in Michigan basements, crawlspaces, garages, and storage rooms. Humid basements, crawlspaces with dirt floors, and storage areas with minimal cleaning have the highest populations.
How BTR Treats Cellar Spider Infestations
BTR uses interior web removal plus residual spray chemistry in basement corners, ceiling intersections, window wells, and crawlspace framing. 90-day warranty. Treatment is minimal because cellar spiders are beneficial indoor pest control.
Prevention Tips
Dust and vacuum ceiling corners, basement rafters, and closet corners monthly. Reduce basement humidity to 40 to 50 percent. Seal crawlspace vents with screen. Declutter storage areas.
Frequently Asked Questions About Cellar Spiders
Are cellar spiders dangerous?
No. Cellar spiders cannot bite humans through skin. Their fangs are too small and their venom is harmless. The urban myth that daddy long-legs are the world's most venomous spider is false and has been debunked by scientific testing.
Should I kill cellar spiders?
No. Cellar spiders are beneficial pest controllers. They eat other spiders, ants, mosquitoes, flies, and other small pests. Leaving a small population in basements and garages reduces other pest problems.
Are cellar spiders and harvestmen the same?
No. Cellar spiders are true spiders (8 legs, 2 body segments). Harvestmen (also called daddy long-legs outdoors) are not spiders (8 legs, 1 body segment, no silk, no venom). Both are harmless to humans.
Why are there so many cellar spider webs in my basement?
Cellar spiders do not clean or repair old webs. Each new web is built adjacent to old webs, creating accumulated masses in undisturbed corners. Vacuuming old webs eliminates buildup without harming beneficial spider populations.
Do cellar spiders infest homes like other pests?
Not aggressively. Cellar spider populations are self-limiting and stable. Infestations are indicators of other pest problems (flies, gnats, ants) that the spiders are feeding on. Treating the underlying pest problem often reduces cellar spider numbers naturally.
Cellar Spider Problem? BTR Can Help Today
Free inspection. Licensed Michigan exterminators. 90-day warranty on most services.