Tree damage occurring immediately after an outbreak of Douglas-fir tussock moth, Orgyia Pseudotsugata McD., and stand conditions 10 years later are described. Because of increased radial growth and ingrowth in the 10-year postoutbreak period, good evidence indicates that tree damage caused by the tussock moth may not be as severe in the overall stand dynamics as previously pictured. The insect probably plays a key role as a phytophagous regulator of primary production in some second-growth white fir stands in California and elsewhere.