Moreover, the species also in northern North America from Alaska and Québec across the United States to Wyoming.

Alydus calcaratus is a large (10.0 to 12.0 mm), oblong and mainly blackish-coloured bug.

The hind leg (femora) of the males are thickened and have several strong spines on the underside.

The body is blackish, the dorsum of the abdomen has a bright orange patch, which is visible only in flight.

Alydus calcaratus is phytophagous, the imagines and the nymphs feeding mostly on fallen seeds of various legumes (Fabaceae) especially species of the genera Sarothamnus, Cytisus, Genista and Ulex.