Comments concerning mouse plagues and bamboo, written for me by Dr. Venzano of El Bolson on May 9, 1978 and received from Bill and Hilda Rumboll August 14, 1978. Translated by O.P. "Comments about reproduction and periodic migrations of wild rodents in the Patagonian forests of Argentina and Chile, coinciding with ecologic changes.- Cana colihue Chusquea culei(sic). This species with a rhizome lives 40 years. At the end of its life it flowers and produces seeds which the wild rodents eat, 80% of which are Oryzomys longicaudatus longicaudatus and other species whose names I can give you from El Bolson. A few months after the flowering these Oryzomys and others increase so much that they emigrate by millions (year 1900 and year 1940. Otto Urban, Chile, says 1860-1900). These rodents are normally arboreal. Personal observations of Dr. Rodolfo Venzano: * "Large numbers of Oryzomys enter the rivers and large lakes where fishes eat them ("perca"=Wild Patagonian trout up to 10 kilos each, and Rainbow Trout=Salmon trout which are caught with rodents in the digestive system When swimming in the water, Oryzomys longi longi lives only a few minutes. * "These small rodents eat fields of wheat, bark of trees (Libocedrus chilensis o "cipres". * "They were entering houses where they ate part of the ear and fingers of babies (Valley of the Rio Manso). * "They were climbing mountains where they were dying in the snows and ice. In 1946 during an excursion with Dr. H. Neumeyer to the glacier of the Rio Esperanza Norte, I encountered thousands of these rodents