Q: Do all spiders bite, and are they poisonous?
A: There are two problems with this question: a technicality, and a set of false assumptions.
First, the technicality. “Poisonous” and “venomous” are two different things. No spider is poisonous — harmful to eat, breathe, or touch. Mushrooms are sometimes poisonous, but spiders are not. Spiders are venomous; their toxins are proteins which only work when injected.
Second, all spiders do bite, but most local spiders are harmless because they are not aggressive and will not bite indiscriminately, or their fangs are simply too small to nip through our comparatively thick skin. Just because they are venomous does not mean they are
dangerous to people.
Spider venom does not exist to harm creatures which are too large for spiders to eat, like humans. The purpose of spider venom is to subdue the spider’s prey, almost always insects. In brief, it’s an insecticide.
Nevertheless, all larger spiders with a body length of a half inch or more should be treated with caution. Avoid flicking them away from your body. People allergic to bee stings may react more strongly to the bite of a spider than an ordinary person.
Bees and wasps kill more people in the United States in one year than spiders and snakes combined kill in ten years, and dogs and cats kill or injure more people each year than bees and wasps. Yet most people like dogs and cats and fear spiders and snakes.
For More Information: http://www.iflscience.com/brain/why-are-we-afraid-spiders
By Dick Brewer
The word is VENOMOUS, not POISONOUS.
Thank you, Dick, for your fun facts of the day! You covered two of the most frequently misunderstood aspects of spiders, clarifying the poisonous/venomous difference, and the fact that spiders do not just march around looking for someone to chomp on. They don’t actually chomp, and most spider bites (what few there are) are the result of being trapped between skin and some article of clothing. Always shake out and inspect gear that you keep in the barn or garage: work shoes, gloves, shirts, etc. to make sure you’re the only thing in your clothes.