What Types of Spiders Are Aggressive?

Most species of spiders are harmless to humans and are rarely aggressive. However, some species of spiders are known to be aggressive bitters, and can cause terrible pain to humans or even death. Different countries and continents have different spiders that show the most aggressiveness and are the most dangerous to humans.

  1. Aggressive U.S. Spiders

    • In the Pacific Northwest, many people consider hobo spiders to be the most aggressive spider. They were even given the common name "aggressive house spiders" to describe their behavior. The aggressiveness of this species is often debated by arachnologists, but hobo spiders are one of the few spiders in the United States that can cause serious harm to humans. However, yellow sac spiders are actually the aggressive spider believed to cause the most spider bite incidents in the United States. They are known to bite repeatedly if they are kept in close contact with a human's skin. Bites can be very painful, and will normally cause dead skin to form over the bite area that will naturally fall off in a few weeks. This species of spider can be found all over the U.S. Other aggressive species of sac spiders can be found worldwide, including Europe.

    Aggressive Australian Spiders

    • The most aggressive spiders in Australia belong to the funnel web family. The Blue Mountain funnel-web spider and the northern tree funnel-web spiders are two aggressive and venomous species, but they are not nearly as dangerous as the Sydney funnel-web spider. The Sydney funnel-web spider is an aggressive spider only found around Sydney, Australia while other funnel-web spiders can be found throughout the country. This species of spider had been known to cause death in bite victims before anti-venom was created. Sydney funnel-web spiders will repeatedly bite a victim, causing lots of pain and other symptoms that need to be treated at a hospital.

    Aggressive South American Spiders

    • The most aggressive spiders in South America are wandering spiders from the family Ctenidae. Wandering spiders are aggressive and territorial. This group of spiders does not build nests or spider webs, but wander around hunting for pray at night. They are a very hairy spider that can have a leg span of 4 or 5 inches. The Brazilian wandering spider is the most dangerous spider in the Ctenidae family and is considered the most venomous spider in the world by the Guinness Book of World Records. They were first discovered in Brazil hence the name, but are located throughout South America. Bites can be life threatening and bitten victims need to seek medical attention immediately. Aggressive wandering spiders can also be found in Central America.

    Aggressive African and Asian Tarantulas

    • Most venomous spiders in Africa are not aggressive, but baboon spiders, also known as tarantulas in the United States, are known to have some aggressive species in the southern portion of Africa. The bites of these baboon spiders will cause vomiting and pain, but they are never fatal. The king baboon tarantula is another aggressive species that lives in Kenya, Tanzania and Uganda. Different types of aggressive tarantulas can be found in the tropical forests of Malaysia, Myanmar, Laos, Vietnam, Philippians and Thailand. These species include the Thailand black tarantula, the Malaysian earth tiger tarantula and the very rare cobalt blue tarantula.