Cockroaches range in size from a few millimeters to 8 cm. They are oval and flattened and the head is concealed under the pronotum. Colours range from brownish, blackish, yellowish, to tawny. They have long running legs. The wings may be well developed, reduced or absent. The antennae are long and hair-like and may be longer than the body. They have chewing mouthparts.

Most beetles have four wings, with the front pair (called elytra) thickened and shell-like or leathery. The hind wings (these are the flight wings) are membranous and when they are not in use they are folded under the elytra. Larvae and adults have chewing mouthparts.

Earwigs are 10-30 mm long, flattened and elongate. The front wings are leathery and very short. They have well-developed cerci at the end of the abdomen that form strong forceps. The antennae are long and simple and they have chewing mouthparts. The legs are similar in size and shape.

The majority of the Diptera are small and soft-bodied insects. They have only one pair of membranous wings. The hind wings are reduced to small knobbed structures called halteres that are used as organs of balance during flight. Many flies also have a calypter or membranous lobe at the base the wings. They have large compound eyes and the mouthparts are adapted for sucking, piercing or sponging. The larvae, called maggots, are legless and wormlike .

Mayflies are small to medium sized, elongate, and very soft-bodied. The abdomen is long and slender with two to three long threadlike tails. Adults have two pairs of membranous wings with numerous veins. The front wings are usually large and triangular and the hind wings are small and rounded. Some species have hind wings that are very small or absent. The wings are held together above body when at rest. The antennae are small, bristlelike, and inconspicuous. The front legs of males are longer than the other legs, sometimes as long or longer than the body. Adults have vestigial mouthparts.

True bugs have sucking mouthparts that form a beak projecting from the front of the head. The structure of the front wings is also a distinctive feature, the basal portion of the front wing is thickened and leathery and the apical portion is membranous. This type of wing is called a hemelytron. The hind wings are membranous and slightly shorter than the front wings. Some species are wingless. The antennae are long and straight.

Homoptera have sucking mouthparts that form a beak that arises from the back of the underside of the head, near the front legs. Winged Homoptera have four wings, with the front pair either membranous or slightly thickened. The wings are held rooflike over the body. There are many wingless species of Homoptera and in some species both winged and wingless individuals occur. The antennae are either very short and bristle-like or long and thin. The range of body size and shape is very variable in the Homoptera.

Hymenoptera have four wings that are joined together by a row of very small hooks, called hamuli. The wings are membranous and have relatively few veins. The front wings are much larger than the hind wings. Some Hymenoptera are wingless. In all Hymenoptera except the sawflies, the abdomen is joined to the thorax by a very narrow connection. The antennae are usually long with many segments. The female ovipositor is usually well-developed and is modified into a sting in many families. Hymenoptera have chewing mouthparts.

Termites are small to medium sized insects, soft-bodied and light-coloured. Most termites are wingless but fully winged adults have two pairs of long, narrow membranous wings that are alike in shape. When winged adults are at rest the wings are held flat over the body and extend beyond the tip of the abdomen. The antennae are long and beadlike. Termites have chewing mouthparts.

Four large membranous wings covered with scales give Lepidoptera their colour and pattern. The adults of butterflies and moths have sucking mouth parts and have a well developed proboscis for drinking nectar or fermenting tree sap. The larvae, called caterpillars, have chewing mouthparts with well developed mandibles. The antennae of butterflies are knobbed at the end, and those of moths are variable but rarely knobbed. When they are at rest, the butterflies hold their wings together vertically over the thorax while the moths hold their wings rooflike over the body. The larvae are usually worm-like with three pairs of jointed legs on the front part of the body and usually five pairs of softer and thicker unjointed legs or prolegs on the middle and hind part of the body.

Mantids have a very distinctive body shape with large eyes on a triangular head. The pronotum is long and the front legs are raptorial for grasping prey. Mantids range from 15 mm to 16 cm long. Many species are camouflaged to resemble foliage, dry sticks, stems or bark, although a few species are brilliantly coloured like the flowers they inhabitat. The wings are fully developed, reduced or absent. The front wings, if present, are leathery. Mantids have chewing mouthparts.

Scorpionflies are slender, medium-sized insects, 18-25 mm long. The lower part of the head is prolonged into a snout with the chewing mouthparts at the end. The wings are long, narrow and membranous and both pairs are similar in size, shape and venation. There is one wingless genus found in Canada. Structure of male genitalia in certain families is bulbous and recurved resembling a scorpion.

Megloptera are large, soft-bodied insects. The wings are long and membranous, with many veins. The hind wings are broader at the base than the front wings and this enlarged area is folded fanwise at rest. When at rest these insects fold their wings over the abdomen. The antennae are long with many segments. Megalopterans have chewing mouthparts that are sometimes very large.

Lacewings are soft-bodied insects with characteristic wing venation. They have four membranous wings with many cross veins and extra branches of the longitudinal veins. The front and hind wings are similar in shape and venation and are usually held roof-like over the body at rest. The antennae are long with many segments. Lacewings have chewing mouthparts.

Dragonflies and damselflies are long, narrow insects 20-125 mm long, often beautifully coloured. The head is large with very large eyes and the abdomen is long and slender. They have four wings that are elongate, many-veined and membranous. The antennae are very small and bristle-like. Odonata have chewing mouthparts.

These insects are relatively large, some as long as 18 cm. They have four wings with the front wings thickened and leathery. The hind wings are broad and membranous and are folded fanlike beneath the front wings when at rest. Some species have the wings reduced or absent. The antennae and ovipositor are long, sometimes as long as or longer than the body. Orthoptera have chewing mouthparts. The hind legs are large and modified for jumping.

Stick insects are 3 to 30 cm long and twig-like or leaf-like in appearance. The wings are often greatly reduced or absent. The front wings, when present, are short and hardened. The antennae are usually long and narrow. The legs are long and not modified for jumping or running. Stick insects have chewing mouthparts.

Lice are small insects with oval or elongated, flattened bodies. They are pale, yellow to brown or bluish, with dark brown or black spots or bands. All lice are wingless. The antennae and eyes are small and the legs are short with strong claws. There are two main groups of lice, recognized by differences in their mouthparts. Sucking lice have specialized sucking mouthparts while chewing lice have chewing mouthparts.

Stoneflies are small to medium insects, flattened, soft-bodied, and dull-coloured. They have four membranous wings which are usually gray or pale brown. The front wings are elongate and narrow and the hind wings are slightly shorter. At rest the wings are held flat over abdomen. The antennae are long with many segments. Stoneflies have long cerci projecting from the end of the abdomen. They have chewing mouthparts.

Fleas are small, wingless insects. They are shiny and dark brown or black. The abdomen is laterally flattened and has many spines and bristles. Fleas have long legs that are modified for jumping long distances. Their eyes and antennae are small and they have sucking mouthparts.

Bristletails are small to medium sized insects, elongate and flattened with small scales covering the body. They are wingless. They have very long antennae and three tail-like appendages at the posterior end of the abdomen. Bristletails have chewing mouthparts.

Caddisflies are small to medium-sized insects from 3 to 30 mm long. They are brown or gray in colour, often with a pattern on the wings. They have four membranous wings covered with small hairs, that are held roof-like over the body when at rest. Some species with very hairy wings can resemble moths. The hindwings are shorter and usually wider than the front wings. The antennae are long, sometimes extremely so. The legs are long. Caddisflies have chewing mouthparts.