Arborvitae weevil

  • Latin name: Phyllobius intrusus Kono
  • French name: Charançon du thuya
  • Order: Coleoptera
  • Family: Curculionidae
Description

Distribution

Western Canada

This Asian species is known only from the lower Fraser Valley in western North America. It is also generally distributed throughout the northeastern United States and southern Quebec.

Micro-habitat(s)

Root, Annual shoot

Damage, symptoms and biology

Damage is first noticeable from May-July as light scorching of shoot tips. On closer examination of the shoot tips, irregular shaped areas chewed out of the shoot tips by feeding adults are visible. Larvae at first feed on fine roots and later on the cambium of larger roots. Damage is indicated by gnawed bark on the roots.

Egg: Cylindrical, about 0.6 mm long and 0.4 mm wide, light brown.

Larva: 0.8 mm in length when newly hatched and 5.8 to 7.0 mm long when mature. Larva is white with pinkish hue when young, becoming creamy white at maturity. The head capsule is yellowish brown.

Pupa: 4.1 to 5.7 mm in length, white with black eyes.

Adult: Female 5.9 to 6.3 mm long and 1.9 to 2 mm wide, male 5.1 to 5.6 mm long and 1.6 to 1.8 mm wide, metallic light green.

The arborvitae weevil overwinters as a mature larva in soil near the roots of the host plant. Pupation occurs in April and adults emerge in May. Adults feed on the tips of the new flush and can be found on the foliage from May to July. After mating, the females lay eggs in small groups, eight eggs on average, in soil near host trees. Eggs hatch in about 15 days. Larvae burrow into the soil where they feed on host roots, completing seven instars before maturing in late fall.

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

Arborvitae weevil

Diet and feeding behaviour

  • Phyllophagous : Feeds on the leaves of plants.
    • Ectophagous: Exposed insect that feeds without penetrating its animal or plant host.
    : Feeds on the leaves of plants.
    • Ectophagous: Exposed insect that feeds without penetrating its animal or plant host.
  • Root-feeding : Feeds on the roots of plants.
    • Geophilous: Lives in or on the ground, or frequently comes into contact with it.
Information on host(s)

In British Columbia the arbor-vitae weevil has been observed feeding on western red cedar and eastern white cedar. Feeding trials have shown that yellow cypress is also vulnerable. Elsewhere, numerous species of cedar, cypress and juniper have been recorded as hosts.

Main host(s)

Eastern white-cedar, western redcedar

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