Though there are countless species of spider found in the United States, only a handful can be considered dangerous or even deadly to humans. The most commonly recognized venomous spider in the US is the black widow spider, followed closely by the brown recluse. Though many people are familiar with, and may be able to identify these spiders, there are several other species that you should be on the lookout for.
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The female black widow spider is easily identified by its black body and the small hourglass shape on the underside of its belly that may vary in color from red to orange or yellow. Though this spider may only grow to a 1/2 inch in size, any bite during which the smallest amount of venom is released can result in serious illness or death. The venom from a black widow attacks the nervous system and may cause headaches, nausea, abdominal pain and pyrexia. The black widow spider is most common in the southern states but they can be found throughout the country.
Brown recluse spiders can be found throughout the United States, though they are most common in the southern states. These spiders can grow up to 3/4 of an inch in length and have a brown, violin-shaped body and six eyes arranged in pairs. The bite of a brown recluse, though it may be painless at first, can result in tissue necrosis and a large, ulcerated sore. Systemic complications including liver and kidney damage have been known to occur as a result of a brown recluse bite but these bites typically only cause large, slow-healing wounds and sometimes permanent scars.
Also called funnel web spiders, hobo spiders can be aggressive, though they infrequently attack humans unless provoked. The bite of a hobo spider can be very painful and the venom may result in necrosis of the surrounding tissue. Many reported cases of brown recluse bites are, in actuality, hobo spider bites. In cases where a bite results in necrosis, the severity is typically less than that associated with the bite of a brown recluse though the wound may take several weeks or months to heal. The hobo spider is typically found in the northwest region of the country though it is said to have originated from Europe.
Yellow Sac Spiders
The yellow sac spider is typically pale in color and can range in size from 5 to 10 mm. These spiders are common throughout the US and they have very powerful fangs that can easily penetrate human skin. The bite of a yellow sac spider can be very painful and redness, itching, and swelling quickly occurs near the bite. In addition to these irritations, lesions and infections are a potential danger with this type of bite. Yellow sac spider bites are among the most common spider bites in the country and they are frequently misdiagnosed as brown recluse bites.
Though native to Australia, mouse spiders have been reportedly seen in the United States. These spiders are a member of the trapdoor spider family and, like most species in this family, burrow into the ground. Mouse spiders can grow up to 3 cm in size and they typically have a glossy black body with a raised, broad head. The bite from a mouse spider can be serious though their attacks rarely include full envenomations. Though the bites can be serious, there are no recorded cases of fatalities linked to mouse spider bites.