Arachnophobia is a serious condition, especially for adventurers, but the most dangerous spiders in the U.S. are enough reason to want to avoid arachnids altogether.

Arachnophobia, the fear of spiders, is one of the most common phobias in the world, and with reason. An adventurer can be mortally wounded by a spider if he tangles with the wrong species.

Here are the most dangerous spiders in the US.

Black Widow

The black widow spider is the common name of any of three species of poisonous North American spiders. The black widow is notorious for the toxicity of its venom to humans. Its bite unleashes a tiny, yet potent, dose of a neurotoxin that sparks local pain, swelling, and – if you get unlucky – respiratory distress and death. The widow’s venom is one of the most potent in the animal kingdom, relative to body size. If bitten by several widows at once, your survival chances are slim to zero. The black widow is easily identified – jet-black in color, with characteristic red markings on the underside of its abdomen. The black widow gets its name from its mating ritual – the much bigger female widow eats the male after mating, probably to suck up the vital nutrients needed for egg-laying. Black widows occur all over North America, but mostly in the northern, western, and southern regions of the continent.

Brown Recluse

Also referred to as the violin spider, the brown recluse can be found in the western and southern U.S. Its body stretches about a quarter of an inch. On the front half of its body, it sports a dark, violin-shaped design, the “neck” of which is formed by a striking furrow on the midline of its back, and the spider’s six eyes are set in two rows. The brown recluse’s venom is extremely deadly – it destroys the walls of blood vessels near the site of the bite, sometimes causing a giant skin ulcer. The wound, which may require several months to heal, can kill. Despite its name, the brown recluse has broadened its range into parts of the northern U.S. and beyond. It rides along with packages in the mail and in vehicles, and may even lurk in your clothing. Its natural home is caves, rodent burrows and other shielded settings. In buildings, it usually occupies quiet spots like attics, storage areas and wall or ceiling voids.

Hobo Spider

The hobo spider resembles the brown recluse, but with hairier legs. Again, like a recluse, the hobo’s venom can cause tissue to die at and around the bite site. The wounds can take months to heal and leave permanent scars. Meantime, one of the easiest to identify symptoms of a hobo spider bite is a thumping and persistent headache that medication can’t eradicate. The hobo spider builds a trampoline-like, funnel-shaped structure of silk sheeting and lurks at the small end of the funnel. Then, it waits for prey to wander into its web. The hobo spider is the leading cause of serious envenomation in the northwestern U.S. Since its introduction from Europe into the Seattle, Washington area in the 1930s, the hobo has been rapidly expanding its reach. It is common around Salt Lake City, Utah.

Yellow Sac Spider

Pale yellow or whitish, the yellow sac spider sits in silk tubes during the daytime and comes out to hunt at night. Its habitat is surprisingly domestic. It favors houses – specifically the top of walls and ceilings. It also hovers outdoors on foliage. The “draglines” it leaves while hunting are one of the most common spiderwebs that you may eradicate with a broom or vacuum cleaner. People sometimes unwittingly brush up against them in the dark, to their regret. The yellow sac spider’s bite is toxic – the venom contains the substance cytotoxin, which can destroy cells much like the venom of a brown recluse. The common symptoms of a yellow sac spider bite are a stinging sensation, followed by redness and swelling. Sometimes, blisters form and burst. The yellow sac hunts for food – usually insects – at night.

Brazilian Wandering Spider

The Brazilian wandering spider is the most venomous spider on earth. Stretching up to five inches across, the highly aggressive creature has a territorial outlook. It is not native to North America but turns up through hitching rides. It is sometimes called the banana spider because it appears in bunches of the fruit. When rattled, the Brazilian wandering spider stands itself up on its back legs, showing its striped arms. In severe bite cases, its potent neuro-toxic venom can trigger shock, paralysis, even death, if medical treatment is not received quickly. You can identify the Brazilian wandering spider by the scarlet hairs covering its fangs. The Guinness Book of World Records ranks the Brazilian wandering spider as the most poisonous spider and the one responsible for the most human deaths.