[2] Cimbex quadrimaculatus is a large species that can reach an adult length of about 19–21 millimetres (0.75–0.83 in).

[3] The body is dark brown to black with extensive yellow markings on the pronotum and abdomen.

The wings are lightly infuscate, while the antennae are predominantly orange with darker scapes.

After hatching, the larvae eat from the edges of their host plants until spinning a cocoon.

[4] Larvae and pupae of Cimbex quadrimaculatus are parasitized by three species of ichneumonid wasp: Listrognathus mactator, Opheltes glaucopterus, and Phobetes nigriceps.