Anti-predator defence behaviour of Argiope appensa (Fuesslin) (Araneae, Araneidae) was studied in the laboratory. The most frequent response of adults and large juveniles of A. appensa to disturbance was pumping, a behaviour during which this web-building spider moved its body rapidly up and down with its legs remaining on the silk. When disturbed, small juveniles differed from adult females and larger juveniles by often dropping from the web instead of pumping. Argiope appensa sometimes put its web betweeen itself and stimuli from potential predators by shuttling from one side of the hub to the other. Argiope appensa occasionally tugged on the web but this behaviour appeared to be primarily a component of prey-catching sequences instead of defence. Experiments were carried out to determine the types of stimuli that elicited pumping. Lightly touching the spider or its web, forcefully hitting the web, and air movement elicited pumping but there was no evidence that chemical stimuli from potential predators were important.