Panorpa communis can reach a body length of about 30 millimetres (1.2 in). The common scorpionfly has a black and yellow body, with a reddish head and tail. The male has a pair of claspers at the end of its tail (for holding the female during mating), giving it a scorpion-like appearance, although it is not a stinger.
The adult insect has a wingspan of about 35 millimetres (1.4 in), with wings that are mostly clear, but have many dark spots or patches. Its head, mounted with large eyes, is drawn into a prominent, downward pointing beak, which opens at the tip of its head.
In the female, the eighth abdominal segment is the shortest, almost twice shorter than the seventh; the sixth is narrowed towards the back. The larva resembles a caterpillar and grows up to 20 millimetres (0.79 in) long. It has three pairs of thoracic legs and eight pairs of prolegs.
Although fully winged, the adults rarely fly very far and spend much of their time crawling on vegetation in damp, shaded places near water and along hedgerows. Panorpa communis is a univoltine species. Eggs are laid in soil annually and the larvae both scavenge and pupate there.