Fun spider facts PMPs need to know

Cobweb spiders were found in 100% of homes in a recent
survey in North Carolina.  

Last year an article was published by Matthew Bertone and colleagues at North Carolina State University about arthropods found in homes.  The only organism found in 100% of the homes and over 90% of the basements surveyed was spiders.  The only other organisms that came close were flies and ants and carpet beetles.  By contrast, German cockroaches were found in only 6% of homes and fleas in 10% of homes.

What this tells me is that everyone in pest control needs to know something about spiders.  So here are some fun spider facts that you can impress your family and friends with.

• Spiders consume an estimated 400-800 million tons of prey every year, at least as much meat as all 7 billion humans on the planet (400 million tons of meat and fish annually).
• The world spider population weighs 29 million tons, as much as 478 Titanics.
• Most spiders kill and eat prey in forest and grasslands (95%) and only 2% of annual spider prey are eaten in agricultural lands, probably because of the regular disturbances caused by farming activities.
• Spiders have been around about 400 million years, longer than all but perhaps the earliest insects.
• Over 45,000 different species of spiders have been described by science.  Only about 3,800 species are known from the U.S. and Canada.
• Half of the different species of spiders in the U.S. are less than 3 mm (1/8 inch).
• Spiders disperse largely by parachuting or "ballooning".  Young spiderlings produce lightweight strands of silk to catch updrafts, especially on sunny mornings. 
• Some spiders have been captured ballooning at altitudes up to 2.5 miles, over 13,000 feet.  It's thought that electrostatic forces assist with flight.
• Spiders feed exclusively on liquids.  They lack jaws to chew food.
• Although nearly all spiders likely have venom, only a handful are capable of causing bites that are medically important to humans.  These include the widow and recluse spiders in the U.S.
• If you ever find yourself walking into an orb-shaped spiderweb, relax.  None of the orb weaver spiders are considered dangerous to humans (For you Hobbit and Lord of the Ring fans, Shelob was more likely a cobweb spider, not an orb weaver).

This post was inspired by a recent Washington Post article by Christopher Ingraham. The fun facts were gleaned from several sources, including the Bertone et al. paper which provided estimates about spider eating capacity; a National Geographic post by Liz Langley;  Evolution of the Insects by Grimaldi and Engel; and Common Spiders of North America by Richard Bradley.  As a handy reference for the common spiders, I heartily recommend the wonderful little book Spiders and Their Kin by Levi and Levi.