Insect identification: common UK insects

There are over 24,000 types of insect in the UK, and some can be tricky to tell apart, even for the experts!

Luckily, some are a little easier to identify, so let's take a look at some of the more common UK insect groups and how to tell them apart using some key features and handy clues.

What is an insect?

Broadly speaking, invertebrates are animals without a backbone. These include multi-legged, hard-bodied minibeasts known as arthropods, as well as corals, slugs and snails, worms and soft-bodied sea creatures. Arthropods can then be separated into groups including crustaceans (such as crabs and woodlice), spiders and insects.

Happily, insects share a number of characteristics to help you separate them from the crowd:

• six legs
• three body sections (head, thorax and abdomen)
• a pair of antennae
• an exoskeleton
• compound eyes
• wings (in most cases)
• a three or four-stage life cycle (egg, larva or nymphs, pupa and adult).

Insects come in a number of groups, or 'orders'. Let's explore eight of the groups you're most likely to spot, and some of their more well-known members.  

Beetles (Coleoptera)

Beetles are one of the most diverse groups of animals on the planet. There are more than 4,000 species found in the UK alone, with around 1,000 of these living specifically in our woods and forests.

How to identify beetles

• Biting or chewing mouthparts.
• Hardened wing cases, with wings folded beneath.
• Four-stage life cycle: egg > larva > pupa > adult.

Species spotlight: 7-spot ladybird

• Active from early spring to autumn, hibernating through winter, sometimes indoors.
• Widespread across the UK in gardens, woodland and grassland habitats, feeding on aphids.
• Expels a nasty-tasting yellow substance from its leg joints when threatened.

Flies (Diptera)

Flies are some of the most common insects in the UK, belonging to families ranging from Diptera (true flies) to Trichoptera (caddisflies). There are around 7,000 species on our shores, from blood-feeding midges and horseflies, to nectar-loving hoverflies and river-dwelling mayflies.

How to identify flies

• Sucking or piercing mouthparts.
• One pair of functional wings.
• Hindwings modified into halteres (used as balancing organs in flight).
• Four-stage life cycle: egg > larva (maggot) > pupa > adult.

Species spotlight: daddy longlegs

• One of around 350 species of UK craneflies.
• Long, ungainly legs and erratic flight pattern.
• Emerge as adults from lawns and grassland in late summer.
• Mostly active at night.
• Contrary to popular belief, not poisonous and cannot bite or sting.

True bugs (Hemiptera)

While all bugs are insects, not all insects are bugs. There are around 2,000 species of true bug in the UK, including  shieldbugs, froghoppers and aphids. They're sometimes mistaken for beetles, but there are lots of differences between bugs and beetles.

How to identify true bugs

• Piercing and sucking mouthparts for feeding on sap, nectar or sometimes blood.
• Membranous wings (but not always).
• Three-stage life cycle: egg > nymphs > adult.

Species spotlight: hawthorn shieldbug

• Speckled green and red wing cases with a distinctive green 'shield' shape in the centre.
• Adults are most active in late summer.
• Feed on the ripening berries of hawthorn, rowan and cotoneaster and are often found in gardens.

Butterflies and moths (Lepidoptera)

Butterflies and moths are some of the UK's most diverse insects. They come in all shapes, colours and sizes, with some moths even mimicking hornets and bumblebees. Certain differences between butterflies and moths split them into separate families, but they're both grouped into the single order, Lepidoptera.

How to identify butterflies and moths

• Large powdery wings (though some female moths are wingless).
• Long tongue, called a proboscis.
• Diet of nectar, juices or animal dung (though many adult moths don't feed at all).
• Four-stage life cycle: egg > larva (caterpillar) > pupa > adult.

Species spotlight: small tortoiseshell butterfly

• Bright orange wings with black and yellow patterns, and a row of bright blue crescents around the wing edges.
• Caterpillars feed exclusively on stinging nettles.
• Adults nectar on buddleia, dandelion, knapweed, ragwort and lots more.

Centipedes and millipedes (Myriapoda)

Myriapoda means 'many legged', which, of course, these weird and wonderful creatures are. There are around 53 species of centipede in the UK and a similar number of millipedes.

How to identify centipedes and millipedes

• Centipedes have one pair of legs per body segment.
• Millipedes have two pairs of legs per body segment.
• Centipedes are predatory carnivores.
• Millipedes are vegetarian, feeding on decomposing plants.
• Four-stage life cycle: egg > nymph > juvenile > adult.

Species spotlight species: white-legged snake millipede

• Shiny, black, cylindrical body with contrasting white legs.
• Found in gardens or woodland, often under rocks or in rotting trees.
• Curls into a ball if disturbed and can release a smelly fluid to deter predators.
• Feeds on fungi and decaying plant matter.

Grasshoppers and crickets (Orthoptera)

Crickets and grasshoppers are often confused, but one key giveaway is their antennae. Crickets generally have antennae longer than their bodies, while grasshoppers have shorter antennae.

How to identify grasshoppers and crickets

• Long, folded hind legs
• 'Sing' by by rubbing their wings (crickets) or legs (grasshoppers) together.
• Three-stage life cycle: egg > nymph > adult.

Species spotlight: meadow grasshopper

• Feeds on long grasses through the summer months.
• Males have longer wings than females.
• Has no hindwings, making it the only flightless grasshopper in the UK.
• Appears in a variety of colours, including green, brown and even bright pink.

Bees, wasps and ants (Hymenoptera)

Hymenoptera is one of the largest and most diverse orders of insects, with around 7,000 species in 57 families found in the UK. These include sawflies which, despite their name, don't belong to the order Diptera.

How to identify bees, wasps and ants

• Two sets of wings (in winged species), the front longer than the back.
• Generally, a narrow waist separating the abdomen from the thorax.
• Some species are social and live in colonies.
• Females of some species can sting.
• Four-stage life cycle: egg > larva > pupa > adult.

Species spotlight: common carder bee

• Ginger-brown all over, with paler hairs on the sides of the thorax and black hairs on the abdomen.
• Males have a pale 'moustache' of facial hair.
• Workers become active in spring, but only queens overwinter to form new colonies.
• Builds nests in old mammal holes, old birds' nests and mossy lawns.
• Feeds from a huge variety of flowers, including comfrey, brambles and viper's-bugloss.

Dragonflies and damselflies (Odonata)

Agile and acrobatic hunters, the UK's 56 species of Odonata are a joy to watch on warm, sunny days.

How to identify dragonflies and damselflies

• Huge eyes for hunting down prey.
• Long, slender bodies.
• Two sets of long, translucent wings.
• Four-stage life cycle: egg > nymph (aquatic) > pupa > adult.

Species spotlight: common blue damselfly

• Active throughout spring and summer, usually near a source of water, but often seen in gardens.
• Males are bright blue and black, while females are a paler grey.
• Generally small and delicate-looking, while dragonflies are much more robust.

Insects are incredibly important. They recycle decaying material. They pollinate plants. They feed a huge variety of birds, mammals and other animals. Without them we would be unable to grow food, and much of the other wildlife we treasure would be lost forever.

Around 350 insects are known to be highly dependent on oak trees, and mixed, native woodlands support even more. With healthy woodlands come abundant insects and thriving people and wildlife.