Black Widow Spider

Black Widow Spider

Behavior

Both Western and Eastern Black Widows spin webs that lack shape and form. Their webs are erratic in appearance, and the silk is stronger than almost all other arachnids. The black widow spider is shy and nocturnal in habit, usually staying hidden in her web., hanging belly upward. Although not aggressive, she may rush out and bite when her web is disturbed or when accidentally trapped in clothing or shoes.

Habitat

On the underside of ledges, rocks, plants and debris, wherever a web can be strung. Cold weather and drought may drive these spiders into buildings.

Food & Hunting

Like most arachnids, the Black Widow preys on insects. Prey caught in the web include a variety of insects (cockroaches and beetles) and other arthropods. After ensnaring its prey in the web, the Black Widow makes small punctures in the victim's body and sucks out the liquid contents. The Black Widow is preyed upon by Mud-Dauber wasps.

The venom of the black widow spider is 15 times as toxic as the venom of the Prairie Rattlesnake, but only a minute amount of the toxin is injected with a single bite by the spider, so they are rarely fatal. However, the relatively large amount of injected rattlesnake venom results in about 15 to 25 percent mortality among those bitten. The bite itself is often not painful and may go unnoticed. But the poison injected by the the Black Widow bite can cause abdominal pain similar to appendicitis as well as pain to muscles or the soles of the feet. Other symptoms include alternating salivation and dry-mouth, paralysis of the diaphragm, profuse sweating and swollen eyelids. Persons younger than 16 and older than 60, especially those with a heart condition, may require a hospital stay. (Heart and lung failure may result in death.) A physician can give specific antivenin or calcium gluconate to relieve pain. Healthy people recover rapidly in two to five days. For others, clean the site well with soap and water. Apply a cool compress over the bite location and keep the affected limb elevated to about heart level. Aspirin or Tylenol may be used to relieve minor symptoms. Treatment in a medical facility may be necessary for children less than 5 years old or for adults with severe symptoms. Call the Poison Center for additional information. Poison Centers across the country now have a new national emergency phone number - 1-800-222-1222 Be very careful when working around areas where black widow spiders may be established. Take proper precautions-wear gloves and pay attention to where you are working. The reaction to a Black widow bite can be painful, and the victim should go to the doctor immediately for treatment. To control the black widow, carefully remove all materials where they might hide. They can be cleaned out of an area simply by knocking down the webs, spiders, and round, tan egg sacs with a stick and crushing them underfoot. Removal or destruction of the egg sacks may help control the population. This spider is resistant to many insecticides.

Curious Facts

  • Black Widow is considered the most venomous spider in North America.
  • The venom of the black widow spider is 15 times as toxic as the venom of the prairie rattlesnake.
  • Black Widow spiders are not usually deadly, especially to adults, because they inject only a small amount of venom.
  • Only the female Black Widow is venomous; males and juveniles are harmless..
  • The female Black Widow hangs belly upward and rarely leaves the web.
  • The Black Widow is also called the "hourglass" or "shoe-button" spider.
  • More than 35,000 spider species of spiders occur in the world. Of these, about
    3,400 species in 64 families are found in North America.

Vital Stats

  • Weight: 1 gram.
  • Length: 1-1.5"
  • Span: 1-3"
  • Sexual Maturity: 70-90 days.
  • Mating Season: Spring
  • Incubation: 14-30 days
  • No. of Eggs: 250-700/sac
  • Birth Interval: 4 to 9 egg sacs/summer
  • Lifespan: up to 3 years
  • Typical diet: insects