The redback spider is one of the most commonly encountered venomous spiders in Australia. Identifiable by a red stripe on the rounded body, these spiders prefer warm sheltered locations and prey on insects, including other spiders. Often found in homes, redback spiders have a venomous bite that’s harmful to humans, causing symptoms such as sweating, nausea, vomiting, headache and other serious effects if anti-venom isn’t given.