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Invading Beetles: Facts, Identification & Control

General Facts

Beetles are members of the order Coleoptera and are the most diverse group of insects on the planet. With over 300,000 species known and documented, most academics agree many more species remain undiscovered throughout the various ecosystems of the world. In Canada alone, scientists estimate more than 9,000 species of beetles either occur naturally or as invasive species introduced through various means. Beetles are identified by their hard outer wings known as elytra and a carapace. They all have chewing mouthparts with powerful jaws. Beetles are diverse in size and colouration ranging from bright colours to brown or black. They feed on variety of foods ranging from plant to animal materials.

Types of Beetles in Canada

As beetles remain one of the largest groups of insects on the planet, species known to the North American continent remain plentiful. Certain families of the insect are more plentiful than others, and many commonly known beetles remain highly recognizable and even helpful to humans. For instance, the common ladybug, also known as a lady beetle, feeds on aphids and other crop-destroying insects, while species from the ground beetle family Carabidae prey on garden pests. Other species may prove more invasive and destructive. For instance, powderpost beetles infest man-made wood structures and wood products, often travelling to wherever homebuilding supplies go as unnoticed stowaways. Members of the carpet beetle family feast on furs, leathers, wools, and silk. Homeowners commonly mistake carpet beetle damage for property destruction caused by moth infestations.

Appearance / Identification

With so many individual species, beetles vary greatly in size, shape, and appearance. All adults possess two pairs of wings and chewing mouthparts, with a body usually hardened and durable. The harder outer wings, or the elytra, cover the membranous flight wings and generally form a straight line down the back when at rest. Antennae vary in structure and usually have 11 segments or less. The overall length of the insect may range from 0.25 mm to over 100 mm, with larger beetles mostly residing in tropical regions of the world.


Beetles occupy various habitats around the country. Most species tend to make homes on plants, while some may burrow and tunnel underground or in trees. Some species of beetle are also capable of swimming and spend a majority of time in or around water. While beetles may live just about anywhere, most do not occur in the northernmost Arctic areas of Canada, as the weather proves too extreme for the insects to thrive.

Life Cycle

Beetles undergo complete metamorphosis, consisting of four distinct stages, namely egg, larva, pupa and adult. Much like other insects, a female beetle lays eggs after mating, which eventually hatch into larvae. Eggs typically appear smooth in texture and are laid wherever the species of beetle usually finds a predominant food source, such as in soil, in wood, under bark, on leaves, or even in carrion. Eggs may be singular, but most beetle species in North America lay several thousand at a time. Beetle larvae remain wingless upon hatching and appear similar to either worms or caterpillars. A larva, sometimes called a grub, has anywhere from one to six simple eyes on each side of the head and mouthparts for eating. At the end of the larval stage, beetles form pupation cells in order to develop into adults. Upon emergence, the body of the beetle appears soft and pale, though the hard carapace and elytra soon appear, as does pigmentation.

Signs of Infestation: Beetles in the Home

Depending on the species or family of beetle, signs of infestation may vary greatly. For most wood-boring species, like the metallic wood-boring beetles, larvae bore deep into trees and leave exit holes when emerging as adults. Considered primary invaders because of the predilection to attack healthy trees, the most common sign of wood-boring beetles remains the frass, or the dusty excrement left behind when entering and feeding on a tree. For species of carpet beetles, such as the varied carpet beetle, feeding on animal skins, furs, and carpets occur during larval stages. To properly identify whether infestation proves beetle and not moth, most larvae leave behind brown, shell-like cast skins when moulting. Other species, like the invasive Japanese beetle (Popillia japonica) and Tribolium castaneum, otherwise known as the red flour beetle, feed on both crops and stored foodstuffs respectively. When population density of the red flour beetle proves high enough, grains begin to show a tinted red appearance, while the Japanese beetle leaves behind brittle and skeletonized shells.

Prevention Tips

As with the signs of infestation, most preventive measures for assuring protection from beetles depend on the species. For beetles that feed on wood, such as wood-boring beetles and powderpost beetles, perhaps the most effective prevention comes from using products like varnish in finished wood products. Varnishing seals old holes and prevents new eggs from being laid or hatched. In order to treat trees, early detection remains crucial. For beetles feeding on interiors, such as carpet beetles, prevention may prove difficult, as the insect finds food in obscure places quite easily. Proper sanitation and exclusion may prove to be the most beneficial way to eliminate carpet beetles. Before purchasing foodstuffs, inspect packaging carefully for beetles that feed on crops and grains. Store dry goods in sturdy, airtight containers and keep areas where food is stored clean. Remove older products and goods as necessary. Appropriately labelled products can be used to control and manage infestations. Calling a trained and qualified pest professional is the best to completely eradicate any active beetle infestation.

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