Millions of spiders weave their webs in the U.S, but which are dangerous?
Of the more than 3,000 spiders crawling across America, only three species represent a real danger or threat to humans. While the prevalence of each species is regional, familiarizing yourself with poisonous arachnids is a good idea, as these pests tend to enjoy living in many of the same space as humans. As a general rule, if you feel as though you've suffered a spider bite (evidenced by distinct puncture marks, swelling or changing colors, pain, etc.), seek emergency medical care. To assist in a proper diagnosis, try to bring the offender or its remains with you to the hospital.
The Brown Recluse
Also known as a fiddle-back thanks to the dark violin-like marking on its back, this generic-brown spider typically measures no longer than an inch. Favoring indoor structures where there is little human traffic, the brown recluse often makes itself at home in furniture, attics, heating ducts or other nooks and crannies. Unfortunately, this spider also finds clothing and bedding equally appealing, a practice that accounts for the majority of encounters with people.
When a brown recluse actually punctures flesh, its highly toxic venom attacks the cutaneous tissue---the skin and muscle---surrounding the bite area. This necrotizing venom immediately begins killing the afflicted tissue, and if left untreated by physicians, can result in gangrene, toxic shock or even kidney failure. Yet despite the severity of this spider's venom, fatalities are extremely rare. Most deaths occur among the elderly, small children or those with compromised immune systems.
The Black Widow
Arguably the best-known American arachnid, the female North American black widow has a shiny, jet-black and plump half-inch-long body with the telltale red marking resembling an hourglass on her belly. However, this abdominal mark may vary slightly in color or shape. Often found in seldom disturbed boxes, woodpiles or any other place where they can hide undetected, only the female black widow is dangerous. Males do not bite and generally don't live long, usually falling victim to the jaws of his mate.
The black widow's bite is often instantly painful, as it envenomates victims with a neurotoxin that blocks certain nerve impulses, causing painful cramping and muscle spasms, as well as vomiting or difficulty breathing. In rare cases, paralysis or death can occur, so seek immediate medical treatment for suspected black widow bites. There's even an antivenin for this spider's toxic bite.
The Hobo Spider
Generally found in damp, underground spaces such as basements or cellars in many of the western states as well as the Pacific Northwest, the hobo spider has a brown narrow body with chevron-like marks that measures less than an inch long, though its legs can add another two inches to this arachnid's overall size.
Those who have suffered a hobo spider bite often don't even realize it before they develop a reddened, painful blister that usually bursts in 24 to 36 hours, leaving an open ulceration in the bite area. Other symptoms---some of which mimic those of a brown recluse bite---include nausea, muscle weakness and pain, a very pronounced headache and even impaired vision.
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