How to Identify Black Widow Spiders and Egg Sacs

If you have noticed spiders and spider egg sacs around your home, it is important that you identify them to ascertain that they are not the poisonous variety. Black widow spider bites are poisonous and dangerous to young children, the elderly and pregnant women. Both black widows and their egg sacs should be promptly destroyed if found in and around the home.

Step 1

Examine the spider itself, pointing a flashlight if you need to see into dark corners. Black widows are typically small with a bulbous abdomen. The southern and western black widow spiders often have a red or orange hourglass-shaped spot on its abdomen, while the northern black widow has red bars. Black widow males are solid black. A brown spider with orange or red markings is a brown widow--not a black widow. Young female widow spiders may have orange or red spots or central stripe, with white bars -- some spiders keep their juvenile coloring into adulthood, according to Virginia Cooperative Extension.

Step 2

Look closely at the spider's web. Unlike most spider webs which consist of thin spider silk woven into intricate patterns, a black widow spider web is messy and unorganized, like a cobweb. The strands will not come together to form a definitive pattern. Due to the overlapping strands a black widow spider web is very strong and hard to pull apart. Any webs of this variety around your home most likely belong to black widows.

Step 3

Examine any egg sacs you find. Black widow egg sacs are small, round, and very smooth. They will generally be around the size of an English pea and a black widow may have several egg sacs within her web. A female widow can produce four to nine web sacs, each containing 200 to 400 eggs, each summer.

Step 4

Consider the location of the web. Black widows prefer to nest outdoors and rarely venture inside. They can however, be found in the dark recesses of a pantry or garage.