How to Identify Black Widow Spiders

The black widow spider is a prolific, poisonous insect that resides just about anywhere in North America, but especially in the South and West [source: CDC]. They can show up in places as varied as building construction sites, where there's road construction, debris-filled places, factories, fences, fields, forests, gardens, homes, roof eaves, stores and woodpiles [source: KidsHealth].

So how can you tell when you're face to face (so to speak) with a black widow spider? Here are the identifying characteristics:

  • Black widow spiders are about half an inch (12.7 millimeters) in length, with long legs.
  • Black widow spiders have a shiny black body.
  • Black widow spiders have the well-known hourglass symbol on its abdomen, in red, red-orange or yellow.
  • Black widow spiders are generally non-aggressive. In fact, they will only bite a person if they're touched, trapped or sat upon [source: KidsHealth].

A person who's been bitten by a black widow may not even realize it until about a half hour after the fact [source: KidsHealth]. The actual bite feels like a small pinprick. Here's how to identify a black widow bite:

  • The black widow leaves two small punctures in the skin where it bites its victim.
  • The victim may feel as if he has been pricked by a pin.
  • The bite area may become swollen and painful, usually about 30 to 40 minutes after the person's been bitten [source: KidsHealth].
  • The victim may experience symptoms including rash, itchiness, headache, nausea, sweating, vomiting and weakness [source: UMMC].

If you suspect a black widow bite, get medical help as soon as possible [source: UMMC].