AbstractThe hallmark of the New Zealand giant wetas and tree wetas (Orthoptera, Deinacridinae) is the spectacular display of vertically raised, spine-studded hind legs and loud rasping sounds given off when humans disturb or poke at the insects. This has been termed as defence bahaviour. The important questions about this behaviour should be framed in ecological terms: what are its detailed components, is it produced in the presence of real weta predators (such as ferret, Mustela putorius), and how effective is it against these predators? This chapter explores these questions and try to place the answers into a comparative view of the family as a whole.