The adult cadelle beetle is a shiny black insect with an elongated flattened body. It has a distinct "waist" between the thorax and the wing covers. Males have lots of very fine punctures on the underside of the abdomen, whereas females have fewer coarser punctures. The larva is white to pale grey with a black head, two pairs of black patches on the back and two black horns at the tip of the abdomen.