Language selection

Government of Canada / Gouvernement du Canada

Search

Coleoptera

Beetles are one of the most diverse orders of insects. Those that damage trees are often (but not always; e.g., leaf beetles) wood-boring beetles, which usually chew through tree bark to lay their eggs in the protected, moist, and nutritious vascular tissues beneath. Their larvae feed by tunnelling through these tissues under the bark, compromising the trees’ ability to translocate water and nutrients to growing tissues. Many of these beetles also transmit pathogens, further damaging the trees vital systems.

Morphological characteristics of these insects:

General biology and ecology

Beetles develop by complete metamorphosis (holometabolous development). Most of the beetles found damaging trees in Canada are wood-boring (e.g., bronze birch borer, whitespotted sawyer, and spruce beetle. Exceptions to this habit are the leaf beetles (e.g., aspen leaf beetle) and some other species that feed on other parts like the roots (e.g., strawberry root weevil). For wood-boring beetles, free-living adults chew through the bark to lay their eggs, and the larvae spend their entire feeding stages under the bark or in the wood. As a consequence of feeding within the sheltered and moist environment under the bark, the larvae are unlike the adults. They are pale and bare, with only the head and mouthparts hardened, and have either no or only rudimentary legs. As their food (vascular tissue) is less nutritious than foliage, most wood-boring beetles have only one generation per year, but some may take a few years to mature, overwintering as large larvae or adults under the shelter of the bark. To enable maturation of their eggs, many adult wood-boring beetles feed on foliage or twigs for a brief period in the summer.

Important families in the order Coleoptera that contain tree pests

Listed below are families from this order found in this database. Species listed within the families are linked to the site’s pest fact sheets.

Buprestidae

Adults are generally referred to as metallic wood-boring or jewel beetles because of their iridescent colouration. Larvae are often called flat-headed borers because their heads and bodies appear relatively flat (as compared to round-headed borers of the Cerambycidae, which is another family of wood-boring beetles). Larvae of species within this family bore under the bark or in the wood. They usually are attracted to and attack weakened or stressed trees, but some species can attack and kill otherwise healthy trees. They can also be found in cut logs and branches. Exit holes when adults emerge from the wood following pupation are often D-shaped.

Cerambycidae

Adults are commonly referred to as long-horned beetles. Adults are generally distinguished by their elongated and cylindrical (round in cross section) bodies and their long antennae (hence their common name). Larvae are elongate, cylindrical, white-to-cream-coloured, and found boring in wood. Larvae of this group are known as round-headed borers (as compared to flat-headed borers of the Buprestidae, which is another family of wood-boring beetles). Species within this family usually attack dead (e.g., fire-killed) or cut trees. Some species will attack living trees. Exit holes when adults emerge from the wood following pupation are round as compared to the D-shaped exit holes of Buprestidae.

Chrysomelidae

Adults are referred to as leaf beetles. Adults are smaller beetles (less than 12 millimetres), oval and convex in shape, with relatively short antennae, and often brightly coloured with dark streaks or spots on the elytra. For the species in this database, the heads of the adults are sunken into the prothorax almost to the eyes. Some of these plant-feeding (phytophagous) insects feed on the foliage or flowers of broadleaf trees. Larvae of these beetles feeding on the leaves of trees will often skeletonize them (especially early instars) or only partially consume them giving the leaves a ragged or shot-hole appearance. These beetles are quite common but do not often cause serious damage to trees.

Curculionidae (bark beetles and weevils)