Adult is irregularly oval, usually asymmetrical, one side of the body almost straight while other curved, narrowed in front; strongly convex, the dorsum above the abdominal region sometimes forming a hump. Adult variable in size, form, and colour, such variation depending considerably upon the host plant. Neither the stigmatic nor anal clefts are conspicuous. There is often a slight median longitudinal carina and some shallow depression on the sides. Some examples almost circular in outline; while on the narrow leaves the scales are elongate and narrow. The colour of the mature insect varies from bright castaneous to deep purple black, the tint usually darkening with age.