Running spiders, or sac spiders, do not form webs. Instead they hunt their prey with lightning-quick speed. They are fast and stealthy, ambushing insects that are either unaware of their presence or unable to flee.
The dark reddish head and thorax are in contrast from the tan abdomen. Hind legs are the lightest of the eight, appearing almost white. Their pedipalps are feelers in the front of the face and are large enough to be mistaken for a 5th pair of legs, albeit shorter ones.
All spiders (except Cribellate Orbweavers) have venom used to immobilize or kill their prey. This particular genus of spider is said to have a pretty painful bite to humans, though their venom is not dangerous like a Black Widow or Brown Recluse's. That said, a few reports of an infection arising at the bite site (possibly from scratching or touching it) have been made as well as a lengthy healing time. As every body is different, see a medical professional if you think a spider bite is getting worse or more painful.
Common name: Running Spider
Scientific Name: Trachelas sp.
Adult Size (Length): 3mm to 10mm (0.12in to 0.39in) COMPARE
Identifying Colors: red; brown; white; tan
General Description: biting, venomous, fast
North American Reach (Though Not Limited To*): Alabama; Alaska; Arizona; Arkansas; California; Colorado; Connecticut; Delaware; Florida; Georgia; Hawaii; Idaho; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; Nevada; New Hampshire; New Jersey; New Mexico; New York; North Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Utah; Vermont; Virginia; Washington; West Virginia; Wisconsin; Wyoming; Alberta; British Columbia; Manitoba; New Brunswick; Newfoundland and Labrador; Nova Scotia; Ontario; Prince Edward Island; Quebec; Saskatchewan; Mexico
* Keep in mind that insect reach is not governed by lines on a map and therefore may appear in areas/regions/states beyond those listed above.