Its venom is potent but does most of its damage in the immediate area of the bite. Originally native to South America, the brown recluse is believed to have been inadvertently imported to the United States. The spider is now common in the South and can be found as far north as Massachusetts. Tarantulas are large, hairy wolf spiders that can grow to two inches in body length and five inches overall, including their legs. They are found throughout the Southwest.
Tarantulas look frightening but their venom is very mild.
They rarely bite unless provoked. When irritated they may instead rub special hairs off their bellies and throw them with their hind legs. The hairs can cause a skin rash, though not all people are sensitive to them. Black widow venom is a neurotoxin that causes a spreading paralysis usually beginning with thigh, back and shoulder muscles . Venom of the female brown recluse is more potent than that of the male, but in either case the poison does most of its damage by destroying tissue.