AbstractThis paper includes illustrations, descriptions, and keys to the following eight genera and 42 species:Atheroides serrulatusHaliday,Caricosipha paniculataeBÖrner,Chaetosiphella berlesei(del Guercio),Chaitophorus abditus(Hottes),Chaitophorus albicentrusnew species,Chaitophorus canensRichards,Chaitophorus crucis(Essig),Chaitophorus delicatusPatch,Chaitophorus longipesTissot,Chaitophorus knowltoniHille Ris Lambers,Chaitophorus macgillivrayaenew species,Chaitophorus macrostachyae(Essig),Chaitophorus minutus(Tissot),Chaitophorus monelli(Essig),Chaitophorus neglectusHottes and Frison,Chaitophorus nigraeOestlund,Chaitophorus nigricentrusnew species,Chaitophorus nodulosusRichards,Chaitophorus nudusRichards,Chaitophorus pallipesnew species,Chaitophorus populialbae(Boyer de Fonscolombe),Chaitophorus populicolaThomas,Chaitophorus populifolii(Essig),Chaitophorus pusillusHottes and Frison,Chaitophorus pustulatusHille Ris Lambers,Chaitophorus saliciniger(Knowlton),Chaitophorus versicolor(Koch),Chaitophorus viminalisMonell,Chaitophorus viminicolaHille Ris Lambers,Laingia psammaeTheobald,Periphyllus americanus(Baker),Periphyllus brevispinosusGillette and Palmer,Periphyllus californiensis(Shinji),Periphyllus lyropictus(Kessler),Periphyllus negundinis(Thomas),Periphyllus testudinacea(Fernie),Pseudopterocomma canadensisRichards,Pseudopterocomma hughi(MacGillivray),Sipha agropyrensis(Gillette),Sipha flava(Forbes),Sipha glyceriae(Kaltenbach),Sipha kurdjumoviMordwilko. A host index has been compiled from the material studied and the literature cited.