Oberea oculata (Linnaeus) - Eyed longhorn beetle

Coleoptera: Cerambycidae

IDENTIFICATION

Adult beetles are distinguished from other species of this genus by a comparatively large body (15 to 20 mm long), black head, elytra and antennae. The parallel elytra are covered with a fine ash-gray pubescence.^{23, 25, 121, 128} The legs, pronotum, scutellum and ventral abdomen are rusty orange.^{23, 25, 128} The antennae are shorter than their body and also taper from the base to the apex.^{23, 128} Two (rarely 4) dark spots occur medially on the pronotum.^{23, 128}

HOST TREES

Salix (main host) and Populus.^{25, 121, 128}

LOCATION OF INFESTATION WITHIN THE TREE

Larvae infest living twigs, stems and branches 0.5 to 5 cm in diameter.^{1, 25, 85, 121, 128, 131} Immature beetles maturation feed on leaves and young shoots.^{23, 25, 128, 131}

HOST CONDITION

Healthy or recently dead hosts.^{64, 85, 128}

DISTRIBUTION

Europe and Asia.^{121, 128}

SIGNS AND SYMPTOMS

Immature beetles maturation feed on host leaves.^{23, 128, 131} Longitudinal bite marks may be present and the leaf vein may be damaged.²³

Females chew a small, longitudinal incision in the smooth bark of slender stems and twigs and lay a single egg.^{23, 128} Bark tissue around these oviposition sites becomes callused and necrotic and the egg appears to be "enclosed in a chamber".²³

After emerging from the eggs, larvae feed on the regenerative tissue near the oviposition site and cause dark spots to form on the bark.²³ After feeding in the callused area, larvae excavate straight longitudinal tunnels (36 to 50 cm long and 4 to 7 mm wide) in the central pith of twigs and branches.^{23, 25, 85, 121, 128, 131} Ventilation holes occur at regular intervals and are used to discard frass and woodchips.^{23, 131} Ejected frass accumulates on the twigs.⁸⁵

Pupation occurs in the larval tunnels near the bark surface.^{23, 85, 128, 131} Pupal cells, 4.5 cm long and 8 mm wide, are constructed by plugging off the upper and lower section of the chamber with two wads of coarse, fibrous frass.^{23, 85} Shoots wither after 1 or 2 years of infestation.²³

A - Adult O.oculata oculata (15-20 mm long) with black head and antennae. Note orange pronotum, legs and abdomen.

B - Ash-gray pubescence covering black elytra. Note 2 dark spots on orange pronotum.

C - O.oculata oculata within larval gallery (36-50 cm long).

D - Callused and necrotic tissue surrounding O.oculata oculata oviposition niche.

E - O.oculata oculata larva.

Photo credits

• A Frank Koehler. Bornheim, Germany
• B Gyorgy Csoka, Hungary Forest Research Institute, Image 1231168, www. forestryimages.org, Feb. 5, 2004
• C Stanislav Krejcik, www.meloidae.com
• D Adrian Colston, Wicken Fen National Nature Reserve, England.
• E Gyorgy Csoka, Hungary Forest Research Institute, Image 1231167, www.forestryimages.org, May 23, 2004