Itsy bitsy? Sure, but spiders loom large in hiker phobias. They shouldn't: Only a few subspecies of the black widow and brown recluse can inflict enough damage to cut short a hike. Here's what you need to know about North America's most venomous spiders, from how to avoid them to treating their bites.
Bothersome Biters Many spiders don’t have fangs big enough to sink into human flesh, and the majority that can release venom that has no effect on mammals. Still, a few deliver a painful—but superficial—bite when provoked.
With hairy bodies spanning several inches across, this desert dweller looks scary but hardly ever bites. If you’ve pestered it to that point and it does lash out, don’t worry: Localized pain is the only by-product.
>> Golden silk orb weaver
Found in the Southeast, this spider’s toxic bite hurts, but the resulting redness fades in about 24 hours.
>> Yellow sac spider
Aggressive—with canary yellow coloring—these half-inch hunters are found in the Northeast. Their painful bite may itch for many months after inflicted.
Avoid an Encounter
First, know this: Spiders are not out to get you. Black widows wait for prey in their webs, and while brown recluses hunt, they’re equally timid toward humans. The only time either spider will attack is in self-defense. Use these tips to prevent a chance encounter.
>> Be particularly alert for spiders at night, and between May and September when they tend to be more active.
>> Shake out gear, clothing, and shoes before packing or putting them on. Hunters (recluses and scorpions, for example) roam at night and, when daylight hits, they seek shelter in warm, dry, and protected places.
>> When collecting wood or cleaning old camp shelters, wear pants, long sleeves, and gloves. A spider’s puny fangs can’t pierce clothing.
>> Don’t reach between rocks, around trees, or into caves or crevices—inside or out—without visually inspecting the area first.
>> Before sitting outside, examine and bang your prospective seat to flush out hiding spiders. “Hover in an outhouse,” suggests Linda Rayor, a Cornell University arachnologist, noting that outhouse seats are favorite widow hiding spots and that testicle bites are especially excruciating.
>> In backcountry huts and cabins, stay away from corners. If you’re using a bed or cot, remove old bedding and anything around or under it, and pull the bed a few feet away from the wall.
>> When you’re storing gear for the season, wrap it in plastic. When you unpack it later, shake it out. Backpack compartments and loosely packed tents make perfect recluse nesting dens.
Catch the culprit, fight infection In rare cases, brown recluse bites can create big problems—like this five-inch ulcer (left) shown nine days after an envenomation. If you suspect a bite and spot a spider scampering away, “try to kill and collect it so that it can be identified,” says Jeff Westerfield, M.D., an instructor at the Emory University School of Medicine. “Knowing the species gives doctors a better idea of how to treat the wound.”
You probably won’t feel a thing…at first. Low-level, localized burning is possible, but initially a spider bite can be painless. It’s later—between 10 minutes and two hours—that signs may point to a specific offender.
>> Brown recluse Its venom contains a protein that liquefies tissue. An attack won’t kill you—but within two hours, the venom begins dissolving the skin and subcutaneous fat near the bite. There’s often a minor blister at the center of the resulting bluish, quartersize sinking patch. These blisters can be severe, sloughing off and leaving a necrotic, long-lasting ulcer. The wound is an entry point for secondary infection—the real danger behind a bite. “I make sure that people keep the wound clean and that they’ve have had their tetanus vaccine,” says Westerfield.
>> Black widow
Injecting a tiny shot of powerful venom is enough to immobilize a black widow’s prey, but the amount isn’t sufficient to paralyze accidental human victims. The bite itself may be barely noticeable, but envenomation causes a systemic reaction. “After a few hours or even minutes, you’ll experience stomach, chest, and muscle cramps throughout your body,” says Westerfield, adding that radiating foot pain, weakness, nausea, and anxiety are also common. “The only risk of death is if you’re already seriously sick,” says Westerfield, “but the symptoms are painful, so a widow bite will likely be a trip ender.”