Canthophorus dubius can reach a length of and a width of . The body of these shieldbugs is oval, black or dark blue, sometimes metallic green or bright violet. The margins to the pronotum and corium of the
hemielytra are white. Antennae are black with the second segment smaller than third. The legs are black. Membrane of the
hemielytra is whitish and connexivum shows white bands. This species is very similar to
Canthophorus impressus. A certain identification requires dissection. ==Biology==