Redwood bark beetle

  • Latin name: Phloeosinus sequoiae Hopkins
  • French name:
  • Order: Coleoptera
  • Family: Scolytidae
Description

Distribution

British Columbia

This beetle is distributed in coastal locations from southern Alaska to southern California.

Micro-habitat(s)

Bark, Trunk, Twig

Damage, symptoms and biology

Most damage is restricted to trees planted as ornamentals. The beetle seldom attacks healthy trees, but prefers weakened, dying or dead trees. Infested trees frequently have been weakened by drought, poor site conditions or various diseases such as Phytophthora root rot and Coryneum stem canker. Numerous 1.5-mm to 2.0-mm round holes in the bark indicate the beetle’s presence. Emerging adults may cause twig pruning damage.

Egg: No information is available.

Larva: A white, legless grub with a pale brown head.

Pupa: White, no cocoon.

Adult: 3.2 to 4.5 mm long, 1.8 to 2.2 mm wide; dark mahogany brown to black, with the posterior section of the wing covers bearing two longitudinal rows of toothlike projections. The female beetle initiates attack, selecting a weakened, dying or recently dead tree. After boring into the inner bark, the female excavates an egg gallery of variable length, averaging about 14 cm. The gallery runs parallel to the grain and has a short spur at the lower end. About 50 eggs are deposited in egg niches crowded close together on both sides of the gallery. Newly emerged larvae feed in the sapwood and phloem, excavating larval galleries at right angles to the egg gallery. The larval galleries later run upwards or diverge to various degrees. Pupal cells are usually constructed in the sapwood but in thick-barked areas they may be in the inner bark. Brood development is somewhat extended with some beetles overwintering as adults, others as larvae; overwintering teneral adults emerge from March through May. Overwintering parent adults extend their galleries and oviposit from March to May and the brood from these emerges in August or September. Overwintering mature larvae complete their development and the teneral adults emerge in June or July. There is usually one annual generation and a partial second generation.

Emerged adults frequently feed on small branches of cedars and cypresses, causing breakage and flagging of twigs on affected trees.

Other information

Feeding damage caused by these insects occurs most frequently on trees in urban areas and includes twig and foliage mining, defoliation, twig pruning, root pruning, cambium boring, and sap sucking resulting in chlorosis of foliage.

Canadian Forest Service Publications

Redwood bark beetle

Diet and feeding behaviour

  • Phloeophagous : Feeds on phloem.
    • Borer: Bores into and feeds on the woody and non-woody portions of plants.
  • Xylophagous : Feeds on woody tissues (wood).
    • Borer: Bores into and feeds on the woody and non-woody portions of plants.
Information on host(s)

The redwood bark beetle is frequently found breeding in western redcedar, eastern white-cedar, Leyland cypress and Lawson cypress in British Columbia.

Main host(s)

Eastern white-cedar, Lawson-cypress, Leyland Cypress, western redcedar

Secondary host(s)

Rocky Mountain Douglas-fir, Rocky Mountain juniper, Sitka spruce, western hemlock, yellow-cedar

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