Tectocoris diophthalmus, commonly known as the Hibiscus Harlequin Bug or Cotton Harlequin Bug, is a brightly coloured convex and rounded shield-shaped bug with a metallic sheen that grows to about 20 mm. Adult females are mostly orange and males are both blue and red or orange. The colours are quite variable. It lives in Northern and Eastern Australia, New Guinea and several Pacific Islands in habitats ranging from urban to agricultural and coastal areas. The Hibiscus Harlequin Bugs feed on many species of the Hibiscus family (Malvaceae), as well as cultivated cotton. They will also eat Illawarra flame tree flowers, grevillea and bottlebrush saplings.