10 Ways to Identify an Insect

Become an Expert With This Helpful Guide

When you encounter a new insect in your backyard, you want to know what it’s likely to do while it’s there. Is it going to eat one of your garden plants? Is it a good pollinator for your flowers? Will it lay eggs in the soil or pupate somewhere? You can learn some things about an insect just by observing it for a while, of course, but that’s not always practical. A good field guide or website may provide information about the mysterious visitor, but you need to know what it is first.

So how do you identify an insect you have never seen before? You collect as much information as you can, looking for clues that will place the insect in a taxonomic order. If you have a camera with you or a smartphone with a camera, it's a good idea to take several photos of the insect using the macro (close-up) setting. Then, ask yourself each of the following questions about your unidentified insect. You might not be able to answer all of them, but any information you gather will help narrow down the possibilities. First, be sure you are looking at an insect and not another arthropod cousin. 

01
of 10

Is It an Insect?

Mosquito identification for malaria eradication
Mosquito identification for malaria eradication.

Chris Martin / Getty Images

To be sure you're really looking at an insect, ask yourself these four questions:

  1. Does it have six legs? All insects do.
  2. Are there three distinct body regions—head, thorax, and abdomen? If not, it's not a true insect.
  3. Do you see a pair of antennae? Antennae are a necessary insect feature.
  4. Does it have a pair of wings? Most but not all insects have two pairs of wings.
02
of 10

Is the Insect an Adult?

Yellow butterfly hatching
A yellow butterfly hatching.

Dorling Kindersley / Getty Images

The taxonomic orders are based on the adult forms of insects. If you have a caterpillar, for example, you won’t be able to use most guides or dichotomous keys. There are ways to identify immature insects, but for this article, we are only looking at adults.

03
of 10

Where Does It Live, and When Is It Active?

Honeybee searching for nectar on a vivid magenta flower
A honeybee is hard at work searching for nectar.

Pierre Longnus / Getty Images

Insects live in certain types of climates and habitats. For example, many insects decompose plant matter and are typically found in soil, leaf litter, or in rotting logs. Tropical regions of the world have many unique species of butterflies and moths that you will not find in a temperate zone. Make a few notes about where you found or observed the insect.

Does the insect prefer specific plants? Some insects have important relationships with specific plants, so the plants in the area might be clues as well. A wood borer is often named for the tree it inhabits and feeds on—knowing the name of the tree can lead you to quick identification of the insect.

When is the insect most energetic? Like other animals, insects may be diurnal or nocturnal, or a combination of both. Butterflies require the sun’s warmth to fly, and so are active during the day.

04
of 10

What Do the Wings Look Like?

Close-up of a dragonfly wing
Close-up of a dragonfly wing.

Peter Dennen / Getty Images

The presence and structure of the wings may be your best clue to identifying an insect. In fact, many insect orders are named for a specific wing characteristic. The order Lepidoptera, for example, means “scaly wings.” If you plan to use a dichotomous key to identify the insect, you will need information about the wings to complete the key.

Here are some details to observe:

  • Does the insect have wings, and if so, are they well developed?
  • Do you see one or two pairs of wings?
  • Do the forewings and hindwings look similar or different?
  • Are the wings leathery, hairy, membranous, or covered in scales?
  • Can you see veins in the wings?
  • Do the wings appear to be larger than the body or about the same size as the thorax?
  • How does the insect hold its wings when resting—folded flat against the body or vertically above the body?
05
of 10

What Do the Antennae Look Like?

The Timberman beetle (<i>Acanthocinus aedili</i>) with antennae that are four times the length of its body
The Timberman beetle (Acanthocinus aedili) has antennae that are four times the length of its body.

Jussi Murtosaari / Nature Picture Library / Getty Images

Insect antennae come in a variety of forms and are an important characteristic to examine when trying to identify an insect. If the antennae are not clearly visible, use a hand lens to get a better look, or if you've taken a photo, bump up the image on your phone or computer. Do the antennae appear threadlike or are they club-shaped? Do they have an elbow or bend? Are they feathery or bristled?

06
of 10

What Do the Legs Look Like?

Close-up of a female European praying mantis (<i>Mantis religiosa</i>)
Female European praying mantis (Mantis religiosa).

Möllers / Nature Picture Library / Getty Images

An insect’s legs are adaptations that help it move, eat, and survive predators. Aquatic insects sometimes have legs that look like boat oars, and as you might expect, these legs are made for swimming. Terrestrial insects like ants spend most of their time walking and have legs designed for quick movement on the ground. Look at a grasshopper’s legs. The third pair is folded and much larger than the others. These powerful legs propel the grasshopper through the air and away from predators. Some insects are predators themselves and have front legs designed for catching and grasping smaller insects.

07
of 10

What Do the Mouthparts Look Like?

Honeybee gathering nectar from a daisy
Honeybee gathering nectar from a daisy.

Michael Rauch / Getty Images

The insect world is diverse, and that diversity is well represented by their various types of mouthparts. There are insects that eat leaves, some that chew on wood, others that drink sap or nectar, and even some that prey on other insects.

Is the mouth designed for chewing, piercing, or just drinking? Many flies feed on sugary foods and have a spongelike mouth for collecting sweet fluids. Butterflies drink nectar and have a coiled tube called a proboscis, which uncurls to reach into flowers. Insects that feed on plant matter have chewing mouthparts, designed to break down plant fibers. Predatory insects, such as mantids, also have chewing mouthparts. Some insects, like weevils and aphids, specialize in drinking plant fluids. They have mouthparts that pierce the plant and then suck the fluids from inside.

If you can, use a hand lens or camera to get a closer look at the insect's mouthparts.

08
of 10

What Does the Abdomen Look Like?

European green dock beetle (<i>Gastrophysa viridula</i>) with a swollen abdomen filled with eggs
European green dock beetle (Gastrophysa viridula) with a swollen abdomen filled with eggs.

Alex Hyde / naturepl.com / Getty Images

The abdomen is the third region of the insect body. Like all arthropods, insects have segmented bodies. The number of abdominal segments can vary between insect orders. The abdomen may also have appendages that are clues to the identity of the mystery insect.

Does the insect have abdominal segments? The number of abdominal segments varies from six to 11. For example, silverfish usually have 11 segments. If they are visible, try counting the segments.

Does the insect have appendages at the end of the abdomen? Your mystery insect may have an obvious “tail” at the end of the abdomen or what appears to be a set of pincers. These structures are touch organs called cerci that help the insect feel. Earwigs have modified cerci that function as forceps. Three-pronged bristletails are named for their three cerci.

What is the size and shape of the insect's abdomen? Is the abdomen long and slender like a mayfly's? Does it look swollen compared to the thorax? Some identification keys use these characteristics.

09
of 10

What Color Is the Insect?

Large red damselfly (<i>Pyrrhosoma nymphula</i>) on an Iris leaf above a pond
The large red damselfly (Pyrrhosoma nymphula) is mainly a European species.

Ben Robson Hull Photography / Getty Images

Insects can be quite colorful, with distinct markings that are unique to a certain species.

Are there colors and patterns on the insect wings? You cannot identify a butterfly without knowing the colors and patterns on its wings. Some beetles have iridescent forewings and others have spots or stripes. But it’s not just insect wings that come in every color of the rainbow. Their bodies may also have unique and colorful markings. Monarch butterflies are known for their orange and black wings, but many people don’t notice the white polka dots on their black bodies.

Are there patterns on the insect's body? Note any colors and patterns on the wings and the body of your mystery insect. If there are dots or stripes, try to count them. Some species mimic the colors of others as a means of fooling predators, so your observations need to be as specific as possible.

10
of 10

How Does It Move?

A leaping male Roesel's bush cricket (<i>Metrioptera roeselii</i>) is a European species
A leaping male Roesel's bush cricket (Metrioptera roeselii) is a European species.

Kim Taylor / Nature Picture Library / Getty Images

It's helpful to note how your mystery insect moves, whether in captivity or in the wild.

Does the insect fly, jump, walk, or wriggle? If you observe the insect flying, you know it is a winged insect and can eliminate at least four insect orders (the wingless insects) from your guesses. Some insects, like grasshoppers, prefer to propel themselves with their legs but are capable of flying when necessary. Mantids walk unless threatened, and then they will fly as well. Even if these traits don’t give you definitive answers to an insect’s identity, making notes on their movement patterns will teach you something about how that insect lives.