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This annotated bibliography includes references to 338 papers. Each deals in some way with either the Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), or a related species. Specifically, 210 publications and 82 unpublished documents make some reference, at least, to the Douglas-fir tussock moth; 55 are concerned with other species in the same genus. The subject matter in each paper has been indexed to at least one general topic (General, Taxonomy, Biology, Host Relationships, Outbreaks, Control, Related Material). Most of these general topics have been subdivided into more specific headings. For example, Host Relationships includes separate categories for white fir, grand fir, and Douglas-fir. A complete listing of the references in each general and specific category is presented in the index.
An outbreak of the Douglas-fir tussock moth caused severe defoliation in northeastern Oregon during the period from 1972 to 1974. Aerial application of DOT was used to control the outbreak in 1974. Much of the infected area has been logged to salvage the dead and damaged timber. The purpose of this study was to determine the economic impact of the Douglas-fir tussock moth, the control program and the salvage logging on private recreation businesses in the area of the tussock moth damage. Personal interviews and mailed questionnaires were used to obtain data from the operators of the businesses. Linear regression analysis was done using gross income data from before, during and after the tussock moth infestation to determine if there was a statistical relationship between changes in gross income and the presence of the tussock moth. Business trends in the area affected by the tussock moth were also compared with state park visitation and motel occupancy in all of Oregon. The operators of businesses were questioned about possible reasons for changes in business volume, changes in normal operations as a result of the tussock moth infestation, and visitors actions during the period. Although there was a decrease in business volume during the tussock moth problem there was no evidence to indicate the tussock moth had any appreciable effect on overall business volume or operations in the study area.
Case histories of five tussock moth outbreaks that occurred in California and Oregon between 1935 and 1965 are discussed. Information is given on the size and duration of the outbreaks, the presence of natural control agents and the damage caused. Most of the outbreaks were eventually treated with DDT. However, enough information was available from untreated portions to show the probable trend of natural events in the absence of direct control. Repeated patterns observed in each of the outbreaks enabled certain generalizations to be made about natural population behavior and tree impact. All infestations followed a 3-year cycle with inconspicuous to minimal defoliation the first year, severe foliage loss the second year, and ultimate collapse of the population by the end of the third year. The most severe tree damage occurred in the second year. Additional loss of foliage before population collapse in the third year was usually of minor importance in terms of total impact. Although other natural factors were involved, a virus disease appeared to be the principal cause of insect mortality during collapse.