Western Black Widow Spiders


  • Latin Name: Latrodectus hesperus
  • Size: ½” body and up to 1” long legs
  • Color: A western black widow spider is black and shiny with a red, yellow or white hour glass shape on the abdomen.
  • Shape: Round with eight legs and eight eyes
  • Found in: Western regions of the United States
  • Overview: The western black widow spider is named for the area of the country he resides in. All black widow spiders are poisonous and have an hourglass on their abdomen.

Origin: Western black widow spiders are thought to have originated in Africa.
Climate: They prefer warm dry climates. Western black widow spiders are found in the desert.
Favorite Foods: Flies, beetles and cockroaches are favorite foods of the western black widow spiders. These insects get stuck in the spider’s coarse web. The western black widow is only able to digest liquids. The shells of the insects are found next to the web.
Family:  Females are larger than males, but males have longer legs.  A male western black widow spider will only live a few months where as a female may live up to a year and a half. A female will lay up to 750 eggs. Each egg sac will contain up to 200 eggs and is attached to the web. The sac is about the size of a dime and tan colored. Baby spiders, “Spiderlings”, will eat each other. Those that survive are white and turn black as they grow. A male will mature in 26 to 103 days and a female will mature in 57 to 122 days. Both males and females molt several times.
Unique Facts: The western black widow spider makes a messy web. They prefer dark places and rarely leave their web. The male will leave the web to mate. The male is about half the size of the female.
Signs of a problem: Western black widow spiders build webs close to the ground. They may build a web near or in a trash can, under a rock or around the foundation of a home. A previously occupied pest hole is a perfect place for a western black widow web. When the temperatures start to drop, the western black widow will look for a place to live inside.
Do they attack humans? Yes, the female will attack humans and in rare cases the bite can be deadly to children or the elderly. The venom will cause internal problems like sweating, swelling, dry mouth, abdominal pain and difficulty breathing. If bit, wash the area and seek medical help. A healthy adult can expect a full recovery in about a week with medical treatment.
Stopping an infestation: Western black widow spiders look for dark quiet areas. Always wear gloves and long sleeves when cleaning areas you can’t fully see. Make sure everyone in your family knows how to identify a black widow spider. The easiest way to remember is the hour glass on the abdomen. If you spot a black widow, call a pest control professional. The adult spider will need to be removed and a through investigation for eggs will be conducted. If eggs are found, they will also be removed. Freezing the eggs for several weeks in the freezer has been proven an effective method of terminating them, but leave this to the professionals.

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