The brown recluse spider is typically 6-20mm, light to dark brown with a violin-shaped pattern on its back. It lives 1-2 years, with females laying 50 eggs in sacs from May to July. The spider's venom is potent and destroys tissue, causing dermonecrotic lesions from its bite that can grow large and take months to heal. While rarely aggressive, bites from this spider are most common when pressed against skin under clothing or in gloves.