The insects that invade a dying or dead tree are the immediate cause of death and the principle mediators of early stages of decomposition of the tree. These insects form a large and complex community, the species components of which are restricted to particular habitats. A study of the insect community associated with dead Douglas-fir has revealed an intricate assemblage of species; in this publication only the 70+ species of the order Hymenoptera are discussed. Keys are provided for identification of all taxa, and there are discussions of the families, genera, and species represented. The known biology of each species is described, and an attempt is made to suggest the ecological role of each species within the dead tree. Table 1 and the appendix deal with the extent of tree-host specificity of the species of Hymenoptera.