Venomous Spiders of Medical Importance

Most spiders will only bite humans in self-defense and when feeling threatened. Effects of a spider’s bite are usually like that of a mosquito or bee sting but if the venom is poisonous to humans, then more serious reactions can occur.

Allergic reactions to spider bites.

Widow Spiders

The most common, toxic spiders seen around the home are Black and Brown Widow spiders. Black widows usually strike fear in even the bravest of individuals because of their ability to cause so much pain. Widow spiders are non-aggressive but will instinctively bite if they become trapped next to one’s skin; otherwise, they are quite shy and don’t go out of their way to bite humans.

Female black widow spider – Note the red hourglass under her abdomen.

Female Brown Widow (showing orange hourglass on her underside )

Brown Recluse

Recluse spiders, such as the brown recluse are also toxic and sometimes will cause skin lesions but these spiders are mostly in the southern states up into the southeastern part of Nebraska.  In California, the brown recluse is rarely seen outside the desert area where the Loxosceles deserta is located.  Although different recluse species are found worldwide, most are in Mexico and Central America

Brown Recluse Spider – Note the violin shape on the head.

Spider Venom

Venom in spiders serves two functions, a. To capture and liquefy the insides of its prey for easy digestion; and b. Self-defense. A Black widow may bite if its nesting place, under a rock or log, is exposed. Recluses are known to crawl inside a pile of clothes left overnight. According to California Poison Control, “The biggest problem with Black widow bites is the pain they cause.” Reasons to go to the doctor after being bit by a spider are:
• If the severity of pain and discomfort increases.
• Spreading redness accompanied by pain.
• Any drainage from the bite.

Hearts Pest Management will treat and eliminate spiders on contact. We will web dust around the perimeter of your home and advise you on ways to keep spiders from coming indoors. Call us for more information and to set up an appointment at 800-986-1006.

You’re also welcome to complete the form below and a caring Hearts Pest Management representative will contact you shortly.

For more information on spider bites and prevention, you can visit California Poison Control at
http://www.calpoison.org

References
California Poison Control – Tips About Spider Bites
Wikipedia – Widow Spiders and Recluse Spiders
Mallis, Handbook of Pest Control, Tenth Edition, Saunders College Publishing, 2011.