During the past two years I have found on the exchange lists of most northern, and all Canadian collectors with whom I have done any exchanging, Arsilonche albovenosa Goetze under its synonym Ablepharon Henrici Grt., and on their list of “wants” as uniformly appeared Leucania phragmitidicola Guen. I always sent for Arsilonche, and always received Leucania phragmitidicola. The latter is a common insect, but the former is more rare, and it may be interesting to know how the two can be distinguished. Superficially they are very much alike; generically they differ as follows: Arsilonche has lashed eyes, Leucania has them hairy; the tongue in Arsilonche is weak and short, in Leucania long and corneous; the legs in the former are shorter and more compact than in the latter, and the spurs of middle and posterior tibiæ are much shorter. The vestiture of Arsilonche on thorax and body is entirely hairy, fine and long; in Leucania the hair is somewhat flattened, more scale-like and shorter Arsilonche has also the head more retracted, the abdomen longer and the primaries rather more lanceolate. The secondaries in albovenosa are pure white, in phragmitidicola they are more smoky and have a darker border.