Hylurgus ligniperda (Fabricius) - Red-haired pine bark beetle

Coleoptera: Scolytidae

IDENTIFICATION

Adults are small (4 to 6 mm long and 2 mm wide), cylindrical black-brown or golden-brown beetles.^{4, 44, 93} The entire body is covered with dense yellowish or reddish hairs that are particularly noticeable on the posterior slope of the elytra and on the front of the head.^{44, 93} The elytral apex is convex with a slight indentation but does not have teeth on the declivity.⁸²

HOST TREES

Pinus.⁴⁴ Pinus strobus, P. nigra and P. sylvestris are known host trees occurring in Canada.^{4, 93}

LOCATION OF INFESTATION WITHIN THE TREE

Larvae feed on the inner bark along the stem, roots and root collar.⁴⁴ In standing trees, females oviposit near the root collar.⁹³ These beetles will also attack buried logs or portions of the log in contact with the ground.^{4, 93} Immature beetles maturation feed on the roots and root collar of healthy and stressed seedlings and young saplings (up to 15 cm in diameter).⁹³

HOST CONDITION

Stressed or recently felled trees.⁴⁴ Females oviposit on freshly cut logs, stumps, slash and even seedlings.^{44, 93}

DISTRIBUTION

Europe.^{44, 93} Introduced into Brazil, Chile, Uruguay, Japan, South Africa, Sri Lanka, Australia, New Zealand and North America (near Rochester, New York).^{44, 93}

SIGNS AND SYMPTOMS

Each female constructs a short entrance tunnel leading to an oblique nuptial chamber in the inner bark. From this nuptial chamber the female constructs a long egg gallery that usually runs parallel or at an angle with the grain of the wood.^{4, 93} The egg gallery can be up to l m long and is not always straight; it often meanders and sometimes doubles back on itself.^{4, 44, 93} Galleries may occur along the stem and in the roots and root collar.

The eggs are laid in notches cut in the walls of the egg gallery and are covered with frass. Egg galleries consist of alternating, 10 to 20 cm long sections with and without eggs. As a result, the larvae tend to be found in groups with mature or nearly mature larvae near the nuptial chamber, then groups of successively smaller, even-sized larvae at intervals along the gallery. The larval galleries are initially at right angles to the egg gallery but soon become random so that they make no distinctive pattern.^{4, 44, 93}

As this insect tends to attack severely stressed or recently dead host material, pitch tubes and crown symptoms are usually not evident.⁷⁵ Along with the reddish brown frass found in bark crevices of host material, the presence of small, round exit holes and dark staining caused by associated fungi are other indications of attack.⁹³ Upon emergence, immature beetles seek pine hosts for maturation feeding and bore spiral galleries in seedlings and young saplings.⁹³ Mortality can occur if larger roots or the root collar of host trees are girdled.⁹³

Hylurgus ligniperda has often been associated with many Leptographium species of varying pathogenicity. If these beetles vector a fungal pathogen, reduced height and branch growth, crown thinning, chlorosis and tree mortality may also be evident on standing infested trees.

A - Adult H. ligniperda (4-6 mm long). Note reddish hairs on the declivity and front of the head.

B - H. ligniperda egg gallery.

C - Numerous H. ligniperda adults under the bark.

D - Reddish-brown frass around stump attacked by H. ligniperda.

E - H. ligniperda maturation feeding damage on seedling.

F - H. ligniperda egg gallery (up to l m long) in stump.

G - Various life stages of H. ligniperda.