When A. miliaris (of either sex) is disturbed or grabbed, it emits a sharp rasping noise from its thoracic segments. If its thorax is pinched, it also squirts a clear viscous mucus with unpleasant smell and a bitter taste, faintly alkaline, with many embedded bubbles. This foam comes out as a strong jet from apertures in the thorax, and more gently from other openings in the body (ten in total); it heaps up around the insect and partly covers it