Spiders

Back >
DID YOU KNOW? Of the over 41,000 spider species in the world, only about 25 can be considered dangerous to humans.
  • In the world- There are over 41,000 species of spiders
  • In the US- There are over 3,500 species of spiders
  • Despite the fact that most spiders are venomous, there are only 2 species in the US that are actually dangerous for humans, the Black Widow and the Brown Recluse

Black Widow Spider

  • Black Widows live throughout all four deserts of the American Southwest
  • They can be found on the underside of ledges, rocks, plants, garages, steps and anywhere else where a web can be strung 
  • Widow spiders are the best known and largest of the Cobweb Weavers
  • Like most arachnids, the Black Widow preys on insects.  After ensnaring its prey in the web, it makes small punctures in the victim's body and sucks out the liquid contents   
  • All Black Widows are venomous 

Female Black Widows are shiny black, usually with a reddish hourglass shape on the underside of her spherical abdomen.  Their body is about 1 inch long.  Black Widows spin webs that lack shape and form.  Their webs are erratic in appearance, and the silk is stronger than almost all other spiders.  The female Black Widow lays several batches of up to 750 eggs each in one summer.  The egg case, about 1/2 inch in diameter, is suspended in the web.  It is white to tan in color and has a paper-like texture.  Young Black Widows are colored orange and white when they emerge; they change color about 4 weeks later.  The female Black Widow may live for more than a year and a half.  Females rarely leave their web, but will bite if threatened. 

Male Black Widows wander in search of females but do not feed or bite.  They are not often seen because they are usually eaten by the female after mating.  The male Black Widow is usually brown and is about half the size of the female.  It may have a pair of reddish stripes on the sides of the abdomen.  

The Bite

  • Initially may go unnoticed for several hours
  • Can cause severe abdominal pain, similar to appendicitis, as well as pain to muscles and soles of the feet. 
  • Other symptoms include alternating salivation and dry-mouth, paralysis of the diaphragm, profuse sweating and swollen eyelids 
  • Antivenom is available in most areas
  • Recovery may take several days, but usually occurs without any long-term complications

Brown Recluse Spider

  • Brown Recluse spiders can grow up to 5/16 inch in length. 
  • They are tan to brown color with a violin-shaped marking on the cephalothorax (Head). 
  • They have 3 pairs of eyes situated at the base of the violin marking (most spiders have 4 pair). 
  • They live under rocks & wood in backyards, basements, garages, shoes, and clothes
  • Since they prefer dark places, usually indoors, they are rarely seen
  • They can be found throughout the Midwestern and Southwestern United States

The Bite

  • Bite from Brown Recluse can result in death of tissue surrounding the initial would site
  • Severity and spread of tissue degeneration depends on the amount of venom injected
  • Initial signs and symptoms may include pain (usually presents after 8 hours) itching, inflammation, blistering and red streaking marks around the bite sight
  • Systemic signs and symptoms may include nausea, high fever and chills

First Aid

  • Keep the victim well hydrated (give plenty of liquids for the first 8 hrs.)
  • Have a Tetanus shot update if it has been more than 10 years since your last one.
  • All spider bites posses the potential for a secondary infection and should be washed thoroughly with soap and water or an antiseptic if available
  • Keep victim hydrated-lots of liquids for first 8 hrs.
  • An ice pack may be applied to alleviate pain and swelling in the bite area
  • Have a Tetanus shot update if more than 10 years
  • Antivenom is available for Black Widow bites but is generally only indicated for severe envenomations.  There is no effective antivenom available for brown recluse bites
  • First Aid is of limited help so you will need to call the Poison Center at 1-800-222-1222 for information about treatment
  • Do Not:
    • Cut the area or attempt to suck out the poison
    • Try to capture the spider for identification
    • Apply any substance/chemical to the affected area without consulting the poison center first
  • Hospitalization is not usually required

Spider Bite Prevention Tips

  • Trim weeds and grass around your home and remove debris to discourage insects growth
  • Eliminate or reduce bright outdoor lighting that attracts insects
  • Seal or caulk outside openings that may allow spiders to enter the house
  • Wear gloves and use caution when working in areas where spiders may live
  • Shake out shoes, clothes, towels and linens before use with items that have been stored and undisturbed for long periods of time
  • Have a professional spray around the perimeter of your home twice a year
  • Use caution if using over the counter pesticides as they may pose a threat to young children and pets if used incorrectly