Redback spiders are found throughout Australia and have a distinctive red stripe on their upper abdomen. Mature females are black with a red stripe and grow up to 1 cm, while males are smaller and brown with red and white markings. Redback spiders eat insects caught in their vertical, funnel-shaped webs built in sheltered places like under logs, rocks, or in buildings. Only female redback bites are dangerous to humans, and can cause pain, sweating, nausea and possibly death, though antivenom is available.