Rather robust, black, clothed with dark-gray scales of uniform color. Beak stout, curved, shorter than the prothorax, scaly; frontal fovea not deep. Prothorax wider than long, coarsely granulated and rugose; sides straight, diverging slightly from the base for two-thirds the length, then rounded and narrowed to the tip, where it is strongly constricted; with a broad dorsal channel near the base. Elytra nearly one-half wider than the prothorax, humeri oblique, slightly rounded; sides parallel, then obliquely narrowed, and narrowly rounded at the tip; disc flattened from the suture to the third stria, and from the base for three-fifths the length, striae fine, interspaces slightly convex ; posterior callus prominent ; there is a feeble tubercle on the third interspace at about two-thirds the length. Antennae and legs reddish-brown; tarsi long.

Length 2.8 mm.; 0.11 inch.

One specimen, San Diego, Cal.; Gr. R. Crotch.
Differs from B. restrictus by the tubercle on the third interspace behind the middle, and by the absence of the white spot which occupies a similar position in that species.