Pigeon tremex look like long, cylindrical wasps. The thorax is reddish-brown and the abdomen is marked with yellow and black bands. The wings vary from golden brown to black. The adults of both sexes have pointed appendages at the end of the abdomen. The females also have a long, slender egg-laying organ, called an ovipositor. The adults are from 2.5 to 5 cm long, with the females slightly larger than the males.
The white larvae, 5 cm long, have light brown heads and a black spine at the tip of the abdomen. Their legs are relatively undeveloped.