Call us at 800-860-6272
or email us
Investigations teaching tip for insect anatomy, habitat information, classification,
and more activity ideas.
What Is An Insect?
An insect is an animal that has three main body parts, two compound eyes, two antennae, and six jointed legs. Instead of bones, insects have hard exoskeletons, which protect their soft bodies like a coat of armor! Insects' three body parts are a head, a thorax, and an abdomen. Most insects have one pair of wings, but some have two pairs (four wings total). Their legs and wings are all attached to the middle body segment - the thorax. Insects breathe through tiny holes along the sides of their bodies called spiracles.
Insects are a very diverse group of animals. There are more than 1 million species of insects that have already been discovered, and probably at least that many more that have not yet been discovered and identified! Most insects hatch from eggs and go through several different stages of life, called metamorphosis. Ladybugs and butterflies experience complete metamorphosis. Some insects, such as praying mantises, hatch looking like tiny versions of their parents. They will grow by molting, or shedding their exoskeleton several times, growing into a new slightly larger one each time. Once the insect is an adult, it will not grow or molt anymore.
Caterpillars are insects, but they look a little different than most insects. As you may already know, a caterpillar will soon spin a chrysalis or cocoon around itself and turn into a butterfly or moth! Caterpillars only have six real legs, but they also have some other pairs of legs called "prolegs." It also looks like they have more than three body parts. It turns out that they have 14 body segments, but the head is one, then there are three segments of the thorax, and ten segments of the abdomen. So they also have three main body parts, but the thorax and abdomen are separated into smaller segments.
What Is a Bug?
Certain kinds of insects are called "true bugs." True bugs include aphids, water bugs, stink bugs, and plant bugs (like box elder bugs and cabbage bugs). True bugs have mouth parts that are used to suck (like a straw) and have outer wings that are usually slightly harder than the wings underneath. The outer wings often have some sort of pattern on them. They still have three main body parts, six legs, and two antennae, just like other insects.
Any creature that does not have all of the characteristics listed above is not an insect! What about spiders? They are a lot like insects, but spiders have two body parts and have eight legs, so they aren't insects. Spiders belong to a group of animals called arachnids. Scorpions and ticks are also arachnids.
Sow bugs and pill bugs, which are also called rollie-pollies, centipedes, and millipedes have many more than 6 legs (they usually have 15 pairs of legs!), and lots of body segments. Some other animals that are related to insects and bugs are called crustaceans, which include creatures like crabs and lobsters. None of these are insects, though!
We often call all kinds of creeping, crawling, and flying creatures "bugs." Even though you now know they are not all insects and they are not really even bugs, it's okay to refer to them as bugs at times. The important thing is to know how to tell the difference between an insect and other kinds of creatures.
For detailed information about different types of insects, spiders, and more, check out this site.
More Insect Activity Ideas: