How to Identify Black Widow Spiders in a Home

Knowing what a black widow spider looks like is an important part of identifying it--especially if it is in your home. Familiarize yourself with the black widow spider's appearance to help you keep your home and body safe from them.

Instructions

Identify Female Black Widow Spiders

1. Check for a shiny, black or dark brown body. Black widows often have a sheen.

2. Estimate the length of the black widow's body. Female black widows are often about a 1/2 inch long (or the size of your little finger's nail). The abdomen's diameter can be as small as a 1/4 inch or as big as 3/8 inch. The overall length of the female's body will be between 1 1/2 and 1 1/3 inches.

3. Look at the underside of the black widow spider. Usually, there is a red, yellow or orange hourglass formation on a spherical abdomen. Sometimes, the hourglass will be split or separated into triangles.

4. Spot other red markings or lines around the black widow's spinnerets. Spinnerets are organs that help a spider spin a web and are usually located on the abdomen.

Identify Male Black Widow Spiders

1. Verify that the male black widow's appearance is similar to that of the female black widow.

2. Note the black widow's length. Male black widows are roughly half the size of female black widows. The male black widow's body is smaller than the female black widow's body; it also has longer legs than the female.

3. Inspect the abdomen. Black widow males have red spots above the abdomen and white lines or bar-like shapes that move along toward their sides.

4. Examine the black widow's appendages. The male black widow's pedipalps are swollen in appearance.

Tips & Warnings

• Check corners, crevices and undisturbed areas of your home at night. Black widow spiders are nocturnal and are more likely to appear during evening hours.

• Black widows are most commonly found in regions that are dry and warm.

• While back widow females are often venomous, black widow males are usually harmless.