The Long-Bodied Cellar Spider (Pholcus phalangioides) is what most people are referring to when they mention "Daddy Long Legs" inside a house. They are the primary architects of the "cobwebs" found in Utah basements and garages.
Cellar spiders are easily identified by their delicate, spindly appearance:
The LegsTheir legs are exceptionally long and thin, often 5 to 6 times the length of their bodies.
The BodyThey have small, cylindrical bodies that are usually a pale tan or translucent gray.
The VibrationIf you disturb their web, they will "bounce" or vibrate so fast that they become a blur. This is a defense mechanism to confuse predators.
In Utah’s dry climate, these spiders seek out the most humid and dark parts of the home.
The Tangle WebThey don't build "pretty" webs. They create messy, irregular tangles of silk. Unlike other spiders, they don't eat their old silk, so the webs just accumulate dust and become "cobwebs."
Spider HuntersA surprising fact for your page: Cellar spiders are fierce predators of other spiders. They are known to invade the webs of Black Widows and Hobo spiders to kill and eat them.
Colony LivingWhile not "social," you will often find dozens of them in the same basement or crawlspace if there is a steady supply of small gnats or flies.
Is it true they have the most toxic venom in the world?No. This is an urban legend. Their venom is very weak and not even remotely dangerous to humans.
Why is my basement covered in cobwebs?Cellar spiders are prolific web-builders. Because they leave their old webs behind when they move or grow, the "mess" can accumulate very quickly in undisturbed areas.
How do they survive in such dry areas?They actually struggle with Utah’s low humidity, which is why you almost always find them near floor drains, sump pumps, or in bathrooms.
