McClure, M.S. 1986a Population dynamics of Japanese hemlock scales: a comparison of endemic and exotic communities.. Ecology 67: 1411-1421.

Notes: In Japan both Fiorinia externa and Nuculaspis tsugae were distributed widely among the 13 natural and cultivated stands of Tsuga diversifolia and T. sieboldii but scale densities were innocuous and low relative to those in North America; trees growing outside their natural habitats are presumed to be more susceptible to insect herbivores, presumably due to stress from less adequate growing conditions.