The citrus trunk borer, Pseudonemorphus versteegi (Ritsema) (Coleoptera: Cerambycidae), is the most destructive pest of citrus in the entire northeastern Himalayan region of India. Adult beetles are stout, large in size, measuring 18.0 to 33.3 mm in length with bluish white elytra and 11-segmented filiform antennae. The antennae are 2.71 and 1.61 times longer than the lengths of the bodies of male and female beetles, respectively. These studies reveal and detail sexual dimorphism characters in adult of Pseudonemorphus versteegi.