Balsam woolly adelgid

Balsam woolly adelgid - Characteristic swelling of twigs bearing adelgids after a recent attack on the crown
  • Latin name: Adelges piceae (Ratzeburg)
  • French name: Puceron lanigère du sapin
  • Order: Hemiptera
  • Family: Adelgidae


Quebec, Prince Edward Island, Ontario, Nova Scotia, Newfoundland, New Brunswick, British Columbia


Twig, Trunk, Root collar, Branch

Damage, symptoms and biology

The balsam woolly adelgid causes two types of damage. Affected trunks can be recognized by the presence of the insect covered in white woolly material in bark fissures, causing swelling of the affected areas and an increase in stem diameter. The needles soon start dropping, the crown turns a brick red colour and the insect's feeding activity results in the formation of dense compression wood, reducing the quality of the wood fibre which is used in pulp and paper manufacturing.

The second type of damage results from the insects attacking the shoots. This causes swelling and distortion of the twigs, a syndrome commonly called "gout". Prolonged attack will hinder bud growth and height growth, and may ultimately lead to tree death, starting from the crown.

The earliest sign that can be used to identify the insect is the presence of white woolly masses on the lower bole, and possibly on large branches in the spring and summer. Crown gout is another sign of infestation, regardless of the time of year involved.

Life cycle (East of the Rockies)

Life cycle (East of the Rockies)
Stage/Month J F M A M J J A S O N D

Other information

The balsam woolly adelgid, a species introduced from Europe, was first reported in Canada in 1910, in southern Nova Scotia. After this discovery, the species was found to be gradually dispersing to the other Atlantic provinces. For the most part, the outbreaks observed during the 20th century were sufficiently intensive and persistent to lead to fir mortality in some areas.

Two control methods can be used against the balsam woolly adelgid:

  1. cut the infested trees in winter, when the nymphs are still present, and burn this material on-site to eliminate the risk of future contamination;
  2. strip the bark off felled trees before transporting them to non-infested regions.

Canadian Forest Service Publications

Balsam woolly adelgid

Diet and feeding behaviour

  • Sap-feeding : Feeds on plant sap.
    • Piercing-sucking: Has specialized mouthparts for sucking the fluids from plants, thereby causing deformities or killing the affected plant sections.
Information on host(s)

Main host(s)

Balsam fir

  • Balsam woolly adelgid Characteristic swelling of twigs bearing adelgids after a recent attack on the crown
    Jean-Paul Laplante
  • Balsam woolly adelgid Close-up of the white woolly substance covering adelgids
    Thérèse Arcand
  • Balsam woolly adelgid Appearance of a mature fir forest of repeated crown attacks after several years
    Robert Blais
  • Balsam woolly adelgid Old fir showing red needles after a severe attack on its trunk
    René Martineau
  • Balsam woolly adelgid Top of fir crown broken off following a severe attack and showing characteristic development of top branches
    Claude Monnier
  • Balsam woolly adelgid Balsam fir stem covered with a white woolly substance secreted by adelgids
    Claude Monnier
  • Balsam woolly adelgid Top of balsam fir crown broken off following severe attack
    Claude Monnier
  • Balsam woolly adelgid
    Claude Monnier
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