Ips hauseri (Reitter) - Hauser's engraver

Coleoptera: Scolytidae

IDENTIFICATION

Adult beetles are bright reddish-black, with an elongated body (3.5 to 5.0 mm long) and are completely covered with sparse, yellowish-brown hairs.²⁴ Each elytron has four spines along the declivity.²⁴ The 3^rd spine in the male is finger-shaped and is the widest and longest, whereas in the female, the spines are all uniform.²⁴ The surface of the declivity is matted.⁷¹

HOST TREES

Picea, Larix and Pinus.²⁴

LOCATION OF INFESTATION WITHIN THE TREE

Larvae feed on the inner bark along the entire bole, including the root collar, and in larger branches (inner bark and sapwood).²⁴ Immature beetles maturation feed on the inner bark of brood trees.²⁴

HOST CONDITION

Healthy trees. But stressed, dying and recently cut trees are preferred.²⁴ Mature trees are preferred, but at high populations young trees (5 to 6 cm diameter) can also be attacked.²⁴

DISTRIBUTION

Russia, Kazakhstan, Kyrgyzstan, Tajikistan,Turkey and China.^{17, 42, 72, 73, 74}

SIGNS AND SYMPTOMS

Immature beetles maturation feed under the bark of brood trees creating slightly irregular-shaped feeding galleries that are parallel to the main stem.⁴² Adults emerge from small, round exit holes.⁴²

One central nuptial chamber includes one male and 2 to 8 females.²⁴ Thus, several egg galleries can radiate downwards (most likely) or upwards from the nuptial chamber.²⁴ Longitudinal egg galleries are 8 to 14 cm long and 1.5 to 3.0 mm wide. These galleries are free of frass.²⁴ Females lay 20 to 45 eggs on both sides of the egg gallery.⁴² The intervals between egg niches are shorter near the nuptial chamber than at the end of the egg gallery.⁴² The perpendicular larval galleries are short (3 to 4 cm long) and become wider as the larvae increase in size.^{24, 42}

Symptoms of attack include resin flow from entrance holes, reddish-brown frass in bark crevices, pitch tubes and sparse crowns with partly dead tops and branches.^{24, 42} Attack sites occur over the entire trunk from the top, down to the root collar.²⁴ Therefore, needles of attacked trees often show yellowing or reddening and wilting that usually begins at the top of a tree.²⁴

A - Adult I. hauseri (3.5-5.0 mm long).

B - Elytral declivity of male I. hauseri. Note size and shape of 3rd spine.

C - Drawing of I. hauseri egg (8-14 cm long) and larval (3-4 cm long) galleries.

Photo credits

• A Klaus Bolte, Natural Resources Canada, Canadian Forest Service
• B Drawing from Li, K. and J. Zhou. 1980, Forest Insects in China, Chinese Forestry Press
• C Drawing from Li, K. and J. Zhou. 1980, Forest Insects in China, Chinese Forestry Press