”Drilus flavescens” is one of the most extreme cases of sexual dimorphism in insects. The females of this beetle look like a caterpillar – so called larviform females – completely lacking wings and other adult characters.
Adult males are approximately 10 millimetres long. They have long comb-shaped antennas, probably utilized for detecting pheromones of females. Head and pronotum are black, while elytra are reddish, quite soft and covered of fine upstanding hairs.