B. griseus Lethocerus (Benacus) Benacus is a genus of giant water bug in the hemipteran family Belostomatidae.

[1][2][3] Benacus is a monotypic genus, containing a single species, B. griseus, which is found in North America.

[1][4][5] Benacus was formerly considered a subgenus of Lethocerus.

[3]