Identify a Black Widow Spider

Black Widows, so named for their deadly courtship practices, are believed to be the stuff of nightmares. In reality, these spiders are actually quite beautiful, particularly because of their distinctive crimson markings. Of course, their bite can lead to some severe discomfort so it is important to be able to correctly identify these spiders.

Steps

Identifying Coloring and Markings

  1. Look for red markings on the spider. Look for two blood red triangles in an hourglass shape on the underbelly of the spider. This marking signifies a female southern black widow. A male black widow has a distinctive pattern on the dorsal side (or upper side) of the spider's abdomen that consists of a row of reddish dots and white or yellow lines.[1]
    • Occasionally, the color of the hourglass can be yellow or orange, and every once in a while, you can find a female with only one triangle.
  2. Check that the spider is a shiny black or a shade of brown or gray. Females range from dark brown to a shiny black, with shiny black being the most common color. Males, on the other hand, are a slightly lighter shade than females and are typically brown or gray.[2]
  3. Examine the shape of the abdomen. Black Widows have plump, rounded abdomens that are directly attached to the spider’s thorax, behind the spider's back pair of legs.The abdomen is the same color as the head and is where you will find any distinctive markings on the spider.[3]

Identifying Physical Features

  1. Check that the specimen has eight legs. Like all spiders, black widows have eight legs, which radiate out from their thorax. The hind legs are covered with bristles which the spiders use to help them wrap their prey in silk.[1]
  2. Examine the spider’s face. Look for two horizontal rows that have four eyes each across the face. The furthest right and left eyes on each row protrude out from the spider's face and are slightly larger than the others.
  3. Inspect the head closely for two chelicerae, or fanged jaws. The jaws open laterally, similar to scissors, to inject the spider's enemies with venom.[3]
  4. Measure the spider. If the spider is dead, or you can get close enough to the spider without disturbing it, you might try measuring the spider. A female black widow will measure approximately 1.5 inches (3.8 cm) in length, including the legs. Males are much smaller, measuring approximately 0.75 inches (1.9 cm) in length, including the legs.[2]

Studying the Web

  1. Measure the spider's web and observe it's shape. A black widow's web is typically irregular in shape. The threads are strong, meaning they are a bit thicker looking than other spider webs. The webs look like they are all tangled and messed up, but in reality, they are constructed with precision. The black widow’s web generally has a diameter of approximately one foot (30 cm).[4]
  2. Look for white or light tan egg sacs in the spider's web. The web may contain one or two sacs that hold up to 900 eggs each. They will be roundish in shape and the spider will mostly likely be very near them. Female black windows never leave the 'nest'.
  3. Consider the location of the web. Black widows generally stay in dry and dark hiding spots. They are often found in corners, meter boxes, cellars, wood stacks and under rocks. Black widows live in primarily warm climates and can be found on every continent except for Antarctica. However, they prefer locations within 45 degrees of the equator.

Tips

  • Black Widow spiders spend most of their time hanging upside down in the web, waiting to capture prey.
  • Black widows are not aggressive. Though their bite is dangerous, it is very unlikely you will ever be bitten by one. Your pets, however, may try to play with them and could be at risk for defensive bites, so make sure you keep the house clear of these fortunately distinctive-looking arachnids.

Warnings

  • While the common perception that you will die of a Black Widow bite is incorrect, it will cause some serious pain, nausea, and restriction of breathing. It, however, can be fatal if a child, elderly person, or some who is very sick is bit. Regardless of your age or health, you should go to the hospital if bitten by one of these spiders.[5]

Related Articles

Sources and Citations

  1. ↑ 1.0 1.1 http://www.economyexterminators.com/black_widow_spider.html
  2. ↑ 2.0 2.1 www.westernpest.com/pest-library/black-widow-spider.html
  3. ↑ 3.0 3.1 animals.nationalgeographic.com/animals/bugs/black-widow-spider/
  4. ↑ http://www.orkin.com/other/spiders/black-widow-spider-web/
  5. ↑ http://animals.nationalgeographic.com/animals/bugs/black-widow-spider/
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