Spruce bud scale

  • Latin name: Physokermes piceae (Schr.)
  • French name: Cochenille des bourgeons de l'épinette
  • Order: Homoptera
  • Family: Coccidae
Description

Distribution

Canada

Canada and United States

Micro-habitat(s)

Bud, Twig

Damage, symptoms and biology

The spruce bud scale causes damage to red, black, and Norway spruce by sucking sap from the shoots. Until now, infestations of the scale insect have lasted for a year or two, and seem to have been confined to young plantation trees growing under unfavourable site conditions. The scales occur in groups of three to five at the bases of the branchlets. They excrete large quantities of honeydew on which a black mold may grow, resulting in blackened trees. Heavy infestations weaken trees and can make them more susceptible to various s disease factors, particularly winter drying. The mold clogs the pores of the plant and this interferes with the exchange of gases and further reduces the vigour of the plant. The lower branches become ragged and sometimes die.

The spruce bud scale is globular and mahogany brown. It overwinters at the base of the terminal buds. The scales mature in late June and the eggs are produced beneath the bodies of the females. The eggs hatch in late July and the young nymphs, or crawlers, move to the bases of the new buds and settle down.

Other information

Spruce bud scale infestations appear to arise primarily from adverse site conditions. So far in the Maritimes, they have been brought under control by natural factors.

Canadian Forest Service Publications

Spruce bud scale

Diet and feeding behaviour

  • Sap-feeding : Feeds on plant sap.
    • Free: Moves about freely to feed.
Information on host(s)

Main host(s)

Black spruce, Norway spruce, red spruce

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