Black Widow Spiders Characteristics, Habitat, and Life Cycle

Black Widow Spider

Black widow spiders are one of the most feared species of spiders in the U.S. While there is some merit to the reputation, black widows have gotten a bad rep mostly based on misinformation. While it is true that they are aggressive, venomous, and the females have a venom reserve that is larger than the males’, the actually bite of the black widow is rarely fatal.

In the western United States, the western black widow spider is native to the region and is the spider that is most threatening to humans there. Understanding this species of spider is the best way to learn how to keep it out of your home and prevent bites. It is also the best way to separate fact from fiction (often of the media generated variety).

The Bite of the Black Widow Spider

Spider BiteThe bite of the black widow is usually painless. At most it feels like a small pin prick. Symptoms will appear within an hour and may include rigidity of stomach muscles, sweating, pain, and urine retention. A few people may experience fever, numbness, paralysis (temporarily in different muscle groups), and agitation. The site itself may be red or there may be red streaks near the bite. People who have been bitten by a black widow compare the effects to a bad case of the flu. There is an anti-venom which works very fast but there is some risk of anaphylactic shock so some doctors are hesitant to administer it, leaving the bite victim to deal with the effects of the venom since it can be relatively safer than the cure. It is not a pleasurable experience, by a long shot, but a black widow spider bite is not likely to kill you.

Characteristics of the Black Widow

When mature, the body of the female black widow is about a half an inch. This does not include the legs which are long and spindly. The abdomen is rounded, jet black, and shiny. The color is uniform over the entire body and legs. The only mark on the body that is not black is the red pattern that is on the underside of the abdomen. This pattern is often referred to as an “hourglass,” but can also appear as two triangles (joined or separate), a small bar and triangle, or some light red color in no particular pattern.

Habitat of the Black Widow

Black Widow SpiderWestern black widows are usually found outside, but they can find their way inside from time to time. They prefer to hide during the day but like to build their webs in areas where the insect traffic is high so garages, basements, cluttered areas, near doors or vents, and windows are prime. They are quite shy and like to hide in small areas like a small gap between two bricks, under the bark in firewood (or between stacked logs), in pipe holes in walls, in boots or shoes left outside, in outdoor toys, under outdoor tables, and under awnings. The hide in these areas during the day and come out at dusk to feed.

Life Cycle of the Black Widow

The female western black widow lays her eggs in a sac that is shaped like a tear drop and yellowish in color. Each sac holds about 300 eggs. They also have the ability to store sperm from their first mating so they are capable of producing 10 eggs sacs, or even more, without mating again and without decreasing the number of eggs per sac.

Black widow spiderlings look very different from the adults when they first hatch. The abdomen is white and may have a few black spots while the legs are tan. As the spider matures the abdomen color changes to an olive gray and a white stripe forms on the top of the abdomen. Along the flanks there will appear three diagonal stripes with a small black dot at the upper tip. With each molt the spider gets darker and the white lines fade.

Preventing Black Widow Bites

Spider ControlThe best way to prevent a black widow bite is to limit any encounters with the spiders. Reducing the clutter in and around your home is one of the best ways to keep them away. Spiders and other pests enter a home looking for food, water, and harborage. When you remove the clutter you are removing harborage for the spider and possibly even a food source.

Regular sweeping or vacuuming of door frames, windows, storage areas, corners of rooms, garages, and basements – any place that is not frequently used – will help to remove the spiders. Vacuuming tends to be very effective because their bodies are delicate so this will kill them. When you store clothing, shoes, and gloves in the garage or basement, secure them in bags that are sealed such as twist ties or zipper locks. If you store boxes of seasonal clothing make sure the boxes are sealed and stored off of the floor, away from walls.

Always wear gloves when cleaning up clutter in the yard or in the garage or basement. Check children’s outdoor toys and outdoor furniture before use and always wear gloves when handling firewood. You should also check your firewood before bringing it into the house so you don’t inadvertently bring a black widow into your home.

You can use chemical control and glue boxes, but this is best done by a professional. Any type of control and maintenance should be done on a regular basis because spiderlings have the ability to travel long distances by exhibiting a behavior called ballooning. They can also be carried in on clothing, in boxes, in firewood, and even on furniture or other items.

The western black widow does not quite live up to its deadly reputation, but it is certain a spider you want to avoid and keep away from your family. A good pest control plan with regular maintenance will dramatically reduce, if not completely eliminate, any spider population as well as other household pests.

Don’t let spiders invade your home and harm your loved ones. For affordable, effective and quick spider control, trust Preventive Pest Control. Call today!

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Black Widow Bite photo by David~O, used under CC BY 2.0/ resized from original