Agonopterix argillacea is a moth in the Depressariidae family. It was described by Walsingham in 1881. It is found in North America, where it has been recorded from California to British Columbia and in Manitoba, Ontario, New Brunswick, Nova Scotia, Michigan, South Dakota, Illinois, Texas, Florida and Utah. The larvae feed on Salix lasiolepis, Salix bebbiana, Amorpha fruticosa and Ptelea trifoliata.