Insect Identification 101

There are millions of species of insects presently roaming the world, only some of which we know about. It is estimated that science has discovered about 80% of the world’s insects. Some insects are harmful and others are completely harmless. You can generally identify many just by looking at them: insects like houseflies, butterflies, fleas, wasps, bees, and so on.

However, some insects are difficult to tell apart, like yellowjackets and hornets, which are both types of wasps. Some insects would be completely unfamiliar. For those insects that are similar to one another or completely different from anything you’ve ever seen, how do you successfully identify what you are observing?

Basic Structure

The first step in insect identification is to look at the body, which is divided into three parts: head, thorax, and abdomen. If your unidentified critter doesn’t have such a body, it is not an insect. The head holds the eyes, the mouthparts, and the antennae. The thorax consists of legs and wings (if present; not all insects have wings).

The abdomen often does not have any easily visible distinguishing features, simply making up the hind part of the body. However, they are the site of spiracles, pores through which insects breathe. Furthermore, some insect abdomens have sensory appendages and many female insects have an ovipositor, or egg-laying structure, on their hindmost segment.

Is it an insect or not? Every crawling and creeping tiny creature is not necessarily an insect. Insects are arthropods. Arthropoda is a phylum containing insects, spiders, ticks, centipedes, and millipedes, among other segmented animals with exoskeletons.

Most, if not all, insects have six legs, two compound eyes and multiple simple eyes, and antennae. Spiders and ticks are not insects. They are arachnids. They have eight legs, no antennae, and only two body segments (the cephalothorax and the abdomen).

Activity Time

Knowing the time of the day in which a particular insect is active can also help with identification. Many insects are most active during the heat of the day, around midday. Insects with midday peaks in activity include bees, wasps, and butterflies.

Others, such as mosquitoes, are most active at dawn and dusk. You’re mostly likely to encounter moths at night. Many insects, however, may be encountered at any time of day with similar likelihood.


Where insects live is yet another tool in your identification toolbox. All insects do not live everywhere. For example, you’re likely to find bees and butterflies, but not houseflies, in flower gardens. Bees and butterflies consume pollen and/or nectar from flowers.

Houseflies are most likely to live near livestock as they both eat and lay their eggs in manure. They also may be found in homes, orchards, and near carcasses as they eat sugary foods like fruits as well as decaying plant and animal matter. 

Fleas can be found on the bodies of furry or feathery animals and while they are sometimes without a host, it is rare to find them free-living. Dragonflies and mosquitoes thrive mostly where there is water but mosquitoes can live just about anywhere as long as standing water is nearby.


How they live and feed is also informative. Many insects live and work alone but wasps, ants, and bees, for example, form colonies. Ants are very orderly and some even store food for winter, a trait shared with mammals and birds but few insects.

Some wasps and bees, like yellowjackets and bumble bees, build their nests underground while others build above ground. Some underground bees might be mistaken for wasps but can be distinguished by diet. While wasps feed on fruits and other insects, bees eat nectar and pollen.

True Bugs

While “bug” is a term we often use to describe many types of arthropods, there is a group of true bugs. All true bugs are insects but not all insects are bugs. True bugs have sucking mouthparts, called a proboscis.

It differs from the proboscis of butterflies and bees by being rigid. Butterflies and bees can retract and roll up their proboscis. True bugs cannot. Examples of true bugs include aphids, stink bugs, bed bugs, and cicadas.

Take Your Time

The most important factor in insect identification is patience, especially when you are identifying a completely unfamiliar insect. If you know absolutely nothing about the insect in question, you may need to simply observe it for a while before starting your research. Note its basic structure, the time of day in which you’re seeing it, where you found it, and what it’s doing. These details will make it much easier to determine what you’ve found.

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