Family Philodromidae – Running Crab Spiders

Running Crab Spiders – Family Philodromidae
Live running crab spiders macro photographed
in the wild at Ogle County, Illinois.  
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Philodromus sp.
Philodromus sp.

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.

Running Crab Spider
Philodromus, possibly praelustris. This indoor spider has a mite hitchhiker on its abdomen


Running Crab Spider


  1., Family Pholidromidae – Running Crab Spiders
  2. Paul Hillyard, Private Life of Spiders (New Holland Publishers Ltd, 2007).
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Class Arachnida / Order Araneae: Spiders are the largest group of arachnids.  They are easily recognized by their eight legs, and there are few creatures great or small that elicit such irrational fear in mankind. The vast majority of spiders are completely harmless and offer beneficial services, chief of which is keeping the burgeoning insect population in check. Spider Index | Spider Main