How to Identify Poisionous Spiders

Black Widow (Latrodectus)

• 1

  Carefully trap the spider using a glass vessel. Typical locations for the spiders to produce their webs are beneath logs or large stones, and inside holes in dirt embankments. More rarely they can be found in barns and associated outbuildings.

• 2

  Find the web of the spider. Black widows spin a silken web that is not uniform and has strands running in several directions.

• 3

  Decide which species of black widow can be found in your area. The southern black widow (Latrodectus mactans) frequents the area between southern New England and Florida. The northern black widow (Latrodectus various) lives between New England and Canada. The western black widow (Latrodectus hesperus) can be found in western portions of Texas, Oklahoma and Kansas, and across to the Pacific states.

• 4

  Assess the age of the spider. Newly hatched black widows are white with black spots on their abdomens and a cream-colored hourglass shape. Adult black widows can be identified according to their sex. The female spider has a bulbous abdomen with unmistakable red markings on its underside. These can be in the shape of an hourglass or a sometimes a dot. When mature, it measures 1 1/2 inches with legs extended. The males also have the red hourglass marking but are thinner and usually mottled brown or gray.

Brown Recluse Spider (Loxosceles Reclusa)

• 5

  Decide whether the spider is common to the area. The brown recluse mostly lives in the south-central Midwest with a few less common recluse species living in the Southwestern states.

• 6

  Trap the spider and look for a violin-shaped pattern on the spider's cephalothorax. This is the point at which the legs extend from the body. While this form of identification is useful for adult brown recluses, many younger spiders and those species found in the West have almost no identifiable pattern.

• 7

  Look at the spider's eyes. The recluse spider is unique in having six eyes as opposed to the usual eight. These are arranged in pairs known as dyads. There is one dyad at the front and one at each side.

• 8

  Check the spider's legs. Recluse spiders' legs are covered with fine hairs but lack the thickened spines of other spiders.

• 9

  Look at the spider's abdomen. A brown recluse will be devoid of any kind of markings.