The Armored Scales of Hemlock

  • Mark S. McClure
Part of the Population Ecology book series (POPE)


Two armored scales, Fiorinia externa Ferris and Nuculaspis (formerly Tsugaspidiotus 4) tsugae (Marlatt) (Homoptera: Diaspididae), native to Japan,44,45 were accidentally introduced into the vicinity of New York City at the turn of the nineteenth century,8,42,48 They have since spread into several northeastern states and have become destructive pests of Eastern hemlock, Tsuga canadensis Carriere, their primary host. In addition to Eastern hemlock, these two scales attack many other native and exotic species of conifers.23 A survey that I conducted at two arboretums in Connecticut demonstrated that F. externa can mature and reproduce on Abies (9 species), Cedrus (3 species), Picea (12 species), Pinus (12 species), Pseudotsuga (1 species), Taxus (2 species), and Tsuga (5 species), while N. tsugae matured and reproduced on Abies (2 species), Cedrus (1 species), Picea (3 species), and Tsuga (5 species). The lower number of conifers exploited by N. tsugae probably reflects the much lower abundance of this scale in hemlock forests surrounding the two arboretums, rather than a more restricted host range.23 Both scales were generally more abundant on Abies and Picea than on Tsuga,23 which suggests that the pests may become even more important as they spread farther northward into the natural ranges of these other conifers.


Natural Enemy Scale Insect Scale Population Eastern Hemlock Foliar Nitrogen 
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Copyright information

© Springer Science+Business Media New York 1988

Authors and Affiliations

  • Mark S. McClure
    • 1
  1. 1.Valley LaboratoryThe Connecticut Agricultural Experiment StationWindsorUSA

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