Understanding the Black Widow Spider

The black widow spider is one of three species in North America with a medically significant bite, the other two being the Brown Recluse and Chilean Recluse.

The black widow spider is generally shy and bites when threatened or pressed against the skin. Unlike the others, the bite is not necrotic but is more venomous. It is one of the most venomous creatures in America.

These spiders can live up to three years. Females create as many as nine sacs a summer, containing as many as 750 eggs each. Generally, one to twelve survive, due to cannibalism amongst the young.

The Unique Look of Black Widow Spiders

Spider Control - Croach - Kirkland, WA - Black Widow Spider on BranchBlack widow spiders young start off-white or gray and grow darker with every molting.

Females are generally shiny black with a red hourglass on the underside of their abdomen. They may have red stripes and dots instead.

Males are dark brown to black with red, yellow, or white dots and stripes on the back. Some species are dark brown and may have white or yellow markings on the underside. These often have red legs.

Where the Black Widow Spider Lives

Black widow spiders prefer warm climates. They have been found throughout the United States. They prefer to live near the ground, choosing small holes and cracks to build their webs. Often found in the basement of buildings. Some live in small, abandoned animal burrows.

Within the Croach® service area, they live in Washington, Oregon, Idaho, and Colorado.

They create webs of irregular, sticky, tangled silk. The web catches insects, which the black widow spider wraps up, liquefies and devours. Egg sacs on the web are teardrop-shaped.

Black Widow Behavior

Black widow spiders are nocturnal. Males travel to find females. Females stay near their web, defending it and attacking when food lands. When threatened they use an escape string and flee. If running is impossible they most often play dead, only biting when pressed to skin or eggs are threatened.

These spiders are known for sexual cannibalism where the female eats the male after mating. This only reliably happens in captivity. In nature, males flee to avoid being killed. A well-fed female is less likely to attack her mate. Males seek females that have eaten recently, which they learn from a scent in the web silk.

Black Widow Spider Bite and Treatment

Males and young spiders are not dangerous to humans.

Spider Bite

The severity of a female bite depends on age and physical condition of the victim and how much venom, if any, the spider injects. Dry or low venom bites have little to no pain and may leave fang marks.

A venomous bite begins with acute, local pain and red skin. They may include systemic effects, including severe muscle pain, abdominal cramps, extreme sweating, increased heart rate, elevated blood pressure, muscle spasms, and trouble breathing. Bites are rarely fatal and most dangerous to children.

Treatment

Children and the elderly who are bitten need immediate medical attention. Anyone else experiencing more than localized pain should seek medical attention. If in doubt, see your doctor. Transport children by EMTs to monitor health in transit.

Croach® Spider Control

Black widow spider control includes:

  • Inspection with individualized plan and proposal.
  • Initial treatment to remove webs and sacs, and eliminate existing spiders, including interior.
  • First regular treatment thirty days later, breaks egg cycle and eliminates remaining spiders.
  • Regular treatments to apply product and remove webs, frequency dependent on severity.
  • Complimentary retreats when necessary.
  • Interior treatments upon request (call if you see a black widow spider).

Related Information:
Hobo Spider
Brown Recluse Spider
Yellow Sac Spider
Spider Species
How to Get Rid of Spiders
Spider Blog Page


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