This paper is intended to bring up to date our knowledge of the Nsorth American species of Aradus, and it is supplementary to my Essay on this group published in 1921. (Trans. American Ent. Soc., XLVII: 1-106, pls. I-VII.) It is based largely on Canadian material sent to me by Dr. J. McDunnough, William J. Gerhard, and W. Downes. Although collectors have shown a considerable interest in the genus, very few new species have come to light; and so it seems likely that our knowledge in this direction is nearly complete. However, those who have access to collecting grounds which are comparatively unmarked by civilization may still discover new forms; and their activities are the more to be urged, since these insects are undoubtedly becoming extinct, as forests disappear and suitable habitats are more and more restricted.