White slaut

White slaut -
  • Latin name: Tetracis cachexiata (Guenée)
  • French name:
  • Order: Lepidoptera
  • Family: Geometridae


Quebec, Ontario, British Columbia

This species is generally distributed throughout the southern interior of British Columbia; it also occurs east to Nova Scotia and south to Florida.


Leaf, Needle

Damage, symptoms and biology

Tetracis cachexiata is a relatively uncommon innocuous solitary defoliator.

Mature larva up to 45 mm long. Head, small, flattened, dull yellowish white with dark markings. Body, brown to grey and variously marked with repeating middorsal hourglass pattern. Body slim, wider from segments 6-9. Second thoracic segment with a pair of large angular lateral swellings and small addorsal tubercles. Both abdominal segments 4 and 5 have a pair of subdorsal tubercles.

Larvae are present from early June to late September. Pupation occurs from July to mid-August, and adults emerge in September or May.

Canadian Forest Service Publications

White slaut

Diet and feeding behaviour

  • Phyllophagous : Feeds on the leaves of plants.
    • Free-living defoliator: Feeds on and moves about freely on foliage.
Information on host(s)

Coniferous hosts of Tetracis cachexiata primarily include Douglas-fir, tamarack and white spruce; other hosts include white birch, trembling aspen and willow.

Main host(s)

Balsam fir, balsam willow, Bebb willow, black willow, Douglas-fir, feltleaf willow, golden weeping willow, heartleaf willow, hooker willow, hybrid white willow, laurel willow, littletree willow, Mackenzie willow, meadow willow, Pacific willow, peachleaf willow, pussy willow, red maple, Rocky Mountain Douglas-fir, sandbar willow, satiny willow, Scouler willow, shining willow, silver maple, Sitka willow, tamarack, trembling aspen, violet willow, white birch, white spruce, white spruce, willow

Secondary host(s)

Basswood, bur oak, choke cherry, Douglas maple, eastern hemlock, eastern white pine, grey birch, mountain alder, mountain maple, pin cherry, red oak, red spruce, Sitka alder, white ash, yellow birch

  • White slaut Larva
    Thérèse Arcand
  • White slaut Larva
    Thérèse Arcand
  • White slaut Larva
    Thérèse Arcand
  • White slaut Pupa
    Thérèse Arcand
  • White slaut Adult
    Thérèse Arcand
  • White slaut
    Dion Manastyrski Centre de foresterie du Pacifique, Victoria (Colombie-Britannique) / Pacific Forestry Centre, Victoria, British Columbia
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