Hemlock-decline
Guides
Fiorinia externa
elongate hemlock scale
Fiorinia externa, the elongate hemlock scale, is an invasive armored scale insect native to Japan and southern China. Accidentally introduced to North America around 1908, it has become established throughout the northeastern United States and threatens hemlock (Tsuga) and related conifers. The species is a pupillarial scale, with adult females remaining within their second-instar exuviae. Heavy infestations cause yellowing, premature needle drop, branch dieback, and occasional tree death. It poses particular economic concern for Fraser fir Christmas tree production in the southeastern United States, where it can persist on harvested trees for up to 13 weeks post-harvest.