Silvicultural manipulations are being used to minimize the impacts of the invasive hemlock woolly adelgid (HWA) on eastern hemlock. Thinning is being tested as a means for reducing hemlock vulnerability to HWA because it increases resources for residual trees, and may affect crown growth and foliar chemistry. With the imminent entrance of HWA into these stands, it was critical to understand whether thinning may also result in increased foliage palatability for the HWA. Hemlock woolly adelgid densities have been correlated with foliar concentrations of calcium (Ca), potassium (K), nitrogen (N), and phosphorus (P). Forest Service scientists determined foliar element levels prior to and for 4 years after thinning in northwestern Pennsylvania stands of eastern hemlock. All element concentrations except Ca decreased over time. Thinning by itself did not affect the tested foliar nutrients. Treatment year interaction was significant and evident in the different temporal trajectories of foliar N and K; however, the differences between thinned and unthinned plots within years averaged only 0.03 percent for N and K. The scientists concluded that even though thinning changed the temporal trajectories, the nutritional shifts reflected decreased competition and increased growth and appeared to be a short-term effect of the treatment.