Home / True Weevils (Curculionidae) / Walnut Twig Beetle (Pityophthorus juglandis)

Walnut Twig Beetle (Pityophthorus juglandis)

The walnut twig beetle is a member of the family of Curculionidae beetles. As its name suggests, it is known for feeding on several species of walnut trees.

Walnut Twig Beetle

Scientific Classification

  • Family: Curculionidae
  • Genus: Pityophthorus
  • Scientific name: Pityophthorus juglandis

Physical Description and Identification

Adult

Size: 1.5 to 1.9 mm

Color: These beetles mostly have a reddish-brown body.

Other Characteristic Features: They are small in size, with their prothorax being broken and ragged.

Pityophthorus juglandis

Larva

The larvae are white and C-shaped, also having a brown head capsule, devoid of any legs. They can be found in the phloem of the host plant.

Walnut Twig Beetle Larvae

Pupa

After maturing, the larvae begin to pupate.

Walnut Twig Beetle Pupa

Egg

Eggs are laid in galleries that are horizontal across the grain.

Quick Facts

Lifespan7 weeks
DistributionUnited States; primarily Arizona and New Mexico
HabitatRegions with cold climes
Seasons activeMay- June; September-October
Host plantsButternut, walnut, or wingnut
Diet of adultsSame as host plant
Walnut Twig Beetle Damage

Identifying the Damage Caused by Them

These beetles make galleries in the host plant by burrowing into the bark. In later stages, these galleries increase in size and spread apart by 2-5 cm, essentially stunting further growth of the tree.

Did You Know

  • There is believed to be a connection between this beetle and the fungus Geosmithia morbida, as this fungus soon infects sites attacked by these beetles.
  • The walnut twig beetles were recorded in Arizona for the first time in 1928 in the Arizona walnut tree.
Walnut Twig Beetle Picture

Image Source:

The walnut twig beetle is a member of the family of Curculionidae beetles. As its name suggests, it is known for feeding on several species of walnut trees.

Walnut Twig Beetle

Physical Description and Identification

Adult

Size: 1.5 to 1.9 mm

Color: These beetles mostly have a reddish-brown body.

Other Characteristic Features: They are small in size, with their prothorax being broken and ragged.

Pityophthorus juglandis

Larva

The larvae are white and C-shaped, also having a brown head capsule, devoid of any legs. They can be found in the phloem of the host plant.

Walnut Twig Beetle Larvae

Pupa

After maturing, the larvae begin to pupate.

Walnut Twig Beetle Pupa

Egg

Eggs are laid in galleries that are horizontal across the grain.

Quick Facts

Lifespan7 weeks
DistributionUnited States; primarily Arizona and New Mexico
HabitatRegions with cold climes
Seasons activeMay- June; September-October
Host plantsButternut, walnut, or wingnut
Diet of adultsSame as host plant
Walnut Twig Beetle Damage

Identifying the Damage Caused by Them

These beetles make galleries in the host plant by burrowing into the bark. In later stages, these galleries increase in size and spread apart by 2-5 cm, essentially stunting further growth of the tree.

Did You Know

  • There is believed to be a connection between this beetle and the fungus Geosmithia morbida, as this fungus soon infects sites attacked by these beetles.
  • The walnut twig beetles were recorded in Arizona for the first time in 1928 in the Arizona walnut tree.
Walnut Twig Beetle Picture

Image Source:

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