Among several species of insects which have lately come to the notice of the Division of Entomology of the U. S. Department of Agriculture, through their ravages upon greenhouse violets, is a little species of plant-louse known to florists as the black or brown aphis. The species is now very generally distributed in the United States and occurs in Canada, although it was not known until within five or six years from the time of writing. As it appears to be undescribed, I propose the specific name violœ, and have placed it in the genus Rhopalosiphum, to which it appears to belong. The following description is submitted, pending a more detailed account of the injuries and a consideration of remedies which it is expected will shortly be published by the Department of Agriculture.