Pest Library

Characteristics

The western black widow spider or Latrodectus Hesperus is the only black widow spider species known in the Western part of the United States, although there are several known species in North America. Black widow spiders can be found in British Columbia and expands its territory from Mexico, to the Rocky Mountains, to the Great Plains.

Adult female spiders
• They are 1/2" long, without including the legs.
• Have a round abdomen with unique coloring.
• With a shiny jet black color and a red hourglass on the abdomen.
• Some have a chestnut or purple-colored tinge coloring when they are well-fed, which makes their abdomen expand.

Spiderling
The changes of a spiderling to adulthood will require a couple of molts before they achieve the jet black coloration and the hourglass markings. They will not look like an adult black widow spider compared to other spiders that look like their adult counterpart. When a spiderling exits their sac, they will have light brown legs and cephalothorax with their abdomen appearing white with black spots. The coloring of the spiderling will change as it continuously grows. The abdomen will become olive gray with a vertical white stripe on the top and three diagonal stripes on the bottom. Each diagonal stripe has a small black dot at the top. The stripes will become thinner as the spiderling molts and grow larger. The olive gray will become black and the hourglass will become more pronounced.

Egg sac
• Contains a yellowish dewdrop shape with a narrow shape on the top and fat portion on the bottom.
• They have well-defined margins and looks like a fluffy cotton ball.
• Their sac is strong and is difficult to break open.

Habitat

The black widow spiders are mostly found in California. They prefer to stay in holes, rodent burrows, and rack faces, between bricks, in clutters, in gardens, and just around a home. They create webs that have unrecognizable patters. However, their webs have an above and below threads that contain a vertical support so that can sit down while they wait for their prey to come.

Behavior

This arachnid is a solitary creature. They search for food by themselves. When they are seen with other spiders, they are mating. Mating of this species may mean the demise of the male since the female black spider can become aggressive, which result to the cannibalism of the male spider. After mating, the female black widow will spend her days, creating large webs.

Food

They are carnivores and can eat a variety of insects, ants, bugs, flies, and even other spider species. They can also eat small lizards that get trap on their web.

Life Cycle

Mating happens once the adult male black widow leaves his nest in search for a female. Once the male finds one, the male will stay on the web of the female until they mate. Mating can be dangerous for a male since the female black widow spider is known for consuming their mate. But, in the case of the male escapes, he will search for another female spider to mate and the whole process starts again.

The female spider can produce 300 eggs in one sac and can produce up to 10 eggs or more without the need to further mate. The 10 additional eggs that she can produce will still have the same number of eggs since she has the ability to store sperm after she mates. Maturity for the female spider happens after 90days while the male will become matures after 70 days. The female spider has a year to live after maturity while the male only has less than six months.

Other Information and Tips

Bites are commonly made by the female spider than the male black widow. The bite is often painless or may feel like a pinprick. The place of the bite may create a little red mark or line surrounding the bite. Bite victims may suffer from different symptoms after an hour.

Symptoms include:
• Stiff stomach muscles (which is often mistaken for appendicitis)
• Sweating - sometimes just at the bitten part of the body
• Pain at the bite site or pain that spreads throughout the body
• Inability to urinate (retention)
• Numbness, fever, patchy paralysis
• Victims will move or rock back and forth incessantly to try to lessen the pain

If bitten, get medical attention immediately. Place a cold pack on the site to relieve the pain. Seeking medical attention will help get rid of the venom fast since an anti-venom for black widow spider bites are available. Bite victims can go from extreme pain and back to normal in just 30 minutes.