The Ozark Mountains of Arkansas are currently experiencing red oak borer, Enaphalodes rufulus (Haldeman) populations of epidemic proportions. These beetles forage in living tree phloem and later form galleries in heartwood where pupation occurs. Intensive whole-tree sampling is expensive, time consuming, and laborious. Our objective was to develop a rapid sampling technique to estimate numbers of red oak borer heartwood galleries present in dead trees. We made a series of cross-sectional cuts along the tree bole and counted numbers of holes representing heartwood galleries at the top end of each section. We developed an index that provides a statistically reliable correlation of these hole counts to actual numbers of red oak borer larvae that were present in the heartwood. This provides an easy and accurate method to estimate red oak borer within-tree population densities. Dead trees were sampled from two forest sites exhibiting high oak mortality to determine the total number of heartwood galleries present at tree death. These data were used to explore causal factors in varying beetle densities.