Caenocoris nerii can reach a length of about. The female is larger than the male. Bodies are elongated. The basic color of the body is black, with red markings. Two red quadrangularpatches are present on the head. Two red markings appear on the shoulders of pronotum and at the inner margins of the hemielytra, which only partially cover the membranous blackish wings. Scutellum and abdomen are completely red.