Spiders in the family Philodromidae are commonly known as running crab spiders, after their speed and the fact they run sideways, like their seafood counterparts. One distinguishing characteristic of the running crab spiders is the second set of legs are the longest.

There are 96 species in 5 genera in America north of Mexico. The majority of the species are in the large genus Philodromus.

These spiders are often found indoors, living in the corners of ceilings and walls. However, they hunt prey and do not build webs - you'll have to blame those cobwebs on another spider, perhaps Steatoda.