Insects Facts

Insects ['in-ˌsektz]

Small animals with six legs and a three-part body.

Insects: Facts Insects!!

Boy looking at stick insect on his hand

Some people cringe at the sight of them, other people love to pick them up and study them. Insects are everywhere. In fact, insects are the most numerous creatures on the earth. They live on all of the continents of the world except Antarctica, although a few may have hitchhiked there with human scientists who have gone to study the area.

Set of insects

The scientific name for insects is Heteroptera. It is estimated that there are over a million different species of insects on the earth. Insects compose over 80% of the world's animal population. And within each species, there are literally millions of members. New insects are being discovered all of the time. In fact, scientists believe that there are more species we don't know about yet than we currently have identified. That's really amazing to think about!!

The study of insects is known as entomology. You would think all those entomologists could give a more accurate count of the number of insects on the earth. But counting insects is more or less impossible. The truth is, most insects hide – that is one of the ways that they protect themselves. Many live underground or inside trees and other living things. Lots of them have very short life spans – maybe a few days. This makes it hard to count them. So scientists make estimates based on colonies found in a given area or evidence insects leave behind.

Insect Body


Insects do not have bones like you, but instead have a hard outer covering known as an exoskeleton. This exoskeleton protects their organs and gives them support for moving around. Their bodies are divided into three sections: the head, the thorax, and the abdomen.

Insect closeup

HEAD: The head is where you will find the eyes and mouth. The eyes of insects are much different than those we use to see. An insect has what is called a compound eye. While a human eye has just one lens for sight, the insect's eye is covered in lots of lenses which allows them to see in a wider span around their head. These eyes provide multiple images made up of dots – much the same way as a television works. They don't “see” well, but rely on movement or distance for identifying objects.

Butterfly collecting nectar

The mouth of insects can be one of two forms, depending on the insect. Some have a mouth shaped like a straw called a proboscis that allows them to suck nectar from flowers. Butterflies have this type of mouth. Mosquitos have a variation of this type of mouth which also allows for piercing the skin of a victim to suck out blood.

Other insects have chewing mouths for eating leaves or bark. Ants and termites are perfect examples of chewing insects. The chewing mouths can, in some insects, be used for tearing or cutting – they can even use them as tools to build.

Instead of a nose for smelling like we have, insects have antennae on the tops of their heads. These antennae do the same job our nose can do, but even better. It can help them tell the temperature, locate food, identify egg-laying locations, avoid pesticide, and even find companions. The antennae can even be used for hearing or taste in some species of insects. The antennae can be moved around by muscles in order to point them for a clearer understanding.

Praying mantis

Thorax: Insects are identifiable by their six legs which are attached to the thorax. If they have more than six legs, they are not insects. The legs are jointed just as yours are but have a claw at the end where your foot would be. The claw is used for grabbing and holding things. Some insects have a special pad near their claws that is covered in very fine hairs. This is used for climbing up surfaces that are vertical or smooth like windows and walls. In some insects, such as grasshoppers, the back legs are larger and stronger for hopping. The praying mantis has larger front legs which fold forward and give them the appearance of praying. Some insects can use their legs for digging, grabbing or carrying food or materials to create shelter. Some can even swim.

Red Dragonfly
European Rhinoceros Beetle

Insects fall into two categories; those with wings such as mosquitoes and flies, and those without wings like ants and beetles. The wings, like the legs, are also attached to the thorax. Depending upon the insect, they can have two pairs of wings. Some wings are hard, similar to the exoskeleton, or leather-like. These hard wings are not used for flying but are used for protecting the softer, paper-like wings. Insects with two sets of wings are known as “true bugs.” While we might call all insects bugs, only those with this distinct second set of wings actually qualify.

Abdomen: The abdomen contains all of the internal organs for digestion, breathing, and reproduction. Insects actually breathe through the sides of their abdomen. Their blood carries food but not oxygen so their respiratory and circulatory system is different than humans. Insects' blood is not red, but usually clear or variations of yellow to green.

Life cycle

Insects go through changes during their lives known as metamorphosis. In the insect world, there are two different forms of metamorphosis; simple and complete. Different kinds of insects live in different metamorphic stages.

Simple Metamorphosis

Egg ➲ Nymph ➲ Adult

Nymph of grasshopper

An adult insect lays eggs. The eggs hatch and the resulting life is known as a nymph. Because the outer skin or exoskeleton is hard, they must shed this layer in order to make room for the new-sized body as they grow. During each phase of growth, they are known as an instar. When the nymph can grow no larger it is known as an adult. Nymphs and adults eat the exact same food and have similar physical shape and coloring. Once they become an adult they are then capable of laying eggs and the cycle repeats. Grasshoppers and crickets are examples of insects that go through simple metamorphosis.

Complete Metamorphosis

Egg ➲ Larva ➲ Pupa ➲ Adult

An adult insect lays eggs in this version of metamorphosis, also. This is where the similarities end. The eggs hatch to reveal the larva. Larvae are fairly formless no matter the species. In the case of butterflies, they are called caterpillars - wormlike creatures that do nothing but eat. Flies' larvae are also shaped similarly, but are small, white, and have no identifying marks. The larvae do not eat the same food as the adult. In fact, some insects stop eating once they have passed the larva stage. As the larvae grow, they shed their outer exoskeleton several times.

Green Pupa Stage in the life cycle of a butterfly

At some point, the larva knows to begin a process of becoming a pupa. In this stage, a caterpillar will suspend itself from a branch or other sturdy support and begin to cover itself in a protective covering. Some insects, like bees, have a special place provided for them by the colony to cover themselves up. This is known as a chrysalis or a cocoon. From the outside, it looks as if nothing is happening. But, inside the cocoon, a complete change is happening. The parts of the larva are rearranging – the organs, the muscles, and other body parts are developing into a completely different creature. When the time comes for the adult to appear, which can take from days up to years depending on the species, it will fight its way from the chrysalis or cocoon and what emerges is the adult. Butterflies and bees go through complete metamorphosis.

Check Science Trek's site on Butterflies to learn more about complete metamorphosis.

Insects are Important

Sometimes we are annoyed by insects who bite us or fly in our faces when we are trying to picnic. But they are more than a nuisance. They are a vital part of our environment.

A bee collects pollen from lavender flowers, insect in flight

Without insects to crawl around in flowers as they hunt for their food, we would be without much of our own food. Some insects accidentally gather pollen, which is a dusty material made inside the flower, onto their legs while they move inside of the flowers. Then, when they visit the next flower, this pollen is rubbed off to fertilize and create the mechanism that allows a plant to create fruits or vegetables. This is known as pollination.

In addition to helping to create food for us, they also work to rid us of dead plants and animals. Some species of insect are the key to keeping us from being knee-deep in dead matter. When a plant or an animal dies, insects, bacteria other animals sweep in to eat the remains and turn it into soil through their digestive process. This is the original version of recycling.

Some insects spin a material known as silk which can be woven into fabric. It is considered to be a very valuable material and is used in the making of lots of clothing.

Group of ladybugs on a flower stem, close up

While there are insects that can be pests and cause the human world issues, there are also insects who eat the pests. Some gardeners purposely buy ladybugs to live in their garden and eat pesky insects that would otherwise eat the plants in the garden.

Let's face it, insects can be food for some of our favorite animals. Birds, fish, frogs, and snakes dine on insects all of the time. This is just part of the natural cycle of things. In some parts of the world, humans enjoy snacking on insects too.

Eastern Bluebird Eating Insect

Fun Facts

Here are some facts about insects that you may not know.

Housefly eating sweet
  • Houseflies find sugar with their feet
  • Ants can lift 50 times their own weight at one time
  • Only female mosquitoes bite
  • The queen termite can live for 50 years
  • All insects have 6 legs – if they have 8 they are spiders
  • Termites will communicate with other termites by banging their heads against wood
  • Katydids and walking stick insects camouflage themselves by looking like leaves and branches
  • Some insects can survive being frozen and thawed out again

Top 10 Questions

October 2015

Thanks to William Clark, Director, Orma J. Smith Museum of Natural History, College of Idaho; and Dr. Alan Gillogly, Entomology Curator and Beetle Specialist, Orma J. Smith Museum of Natural History, College of for the answers.

  1. What type of bug is the most common?

    If you are considering the number of species, the most common type of bug is the group of beetles called coleopteran. There are about 500,000 beetle species to date. If you are looking at just shear numbers, it would be the ants. There are about 12,000 species of ants and many have huge nests numbering in the millions or hundreds of millions. (From Hans at Snake River Montessori School in Idaho Falls)

  2. How big is the biggest bug in the world?

    First we have to decide how we measure big. If you use weight as big, the biggest insect would probably be the weta. The weta is an insect related to crickets, grasshoppers, and katydids. The weta can weigh up to 71 grams. The elephant beetle and the goliath beetle may weigh just about as much as a weta. If we measure by the longest insect, it would probably be a species of walking stick that can be as long as 33 centimeters. (From Kazia at Taylor's Crossing Public Charter School in Idaho Falls)

  3. What is an exoskeleton?

    The exoskeleton is the hard outer covering of the insect. It acts like a skeleton and serves the same purpose as the internal skeleton of humans. It protects the insect and allows it to do its various functions. It's even waterproof. (From Cooper at Dalton Elementary School in Dalton Gardens)

  4. Do all insects fly?

    Not all insects can fly. Most adult insects have wings and can fly, but some of them have reduced wings and those wings are not strong enough to actually lift the insect. There are others that have completely lost their wings. The only immature insect that we know of that can fly is the mayfly. The nymphs of mayflies live in water and when a nymph molts, it molts into a sub-adult stage, which only lasts for a few minutes. A sub-adult flies to a rock or branch and then molts again into the full adult stage. (From Colin at Cynthia Mann Elementary School in Boise)

  5. How long do insects live?

    It varies. Most insects don't live over one year. Some insects, like the mayfly, only live for a few hours once they emerge from the immature stages. The seventeen year cicada is a good example of an insect with a long life. The nymphs live in the ground for roughly 17 years. Then when the adult emerges, they will live for only a few weeks. There are some beetle larvae that live in wood that may exceed 35-50 years in lifespan, and another outlier is the African termite queen that may live up to 66 years. (From Jada at Cynthia Mann Elementary School in Boise)

  6. What does the thorax do on an insect?

    The thorax is the primary segment for the insect's operations, like flying, walking, jumping and running. The legs and the wings are attached to the thorax, and the muscles that run those appendages are attached to the inside of the exoskeleton. (From Ava at Dalton Elementary School in Dalton Gardens)

  7. What is chitin?

    The exoskeleton of insects is made of chitin. It can be very, very hard or it can be soft and flexible. It's about as strong as the keratin that makes up the fingernails of humans. (From Curtis at Dalton Elementary School in Dalton Gardens)

  8. Is it true that a cockroach can live for seven days without its head?

    It wouldn't function in its normal state or do the things that the insect would do with its head, but it can live because the blood continues to circulate and it lives off of fat deposits that it has stored. The insect still has its nervous tissue inside, so that even without its head, the nervous tissue helps keep some of the basic body functions going. (From Benjamin at Cynthia Mann Elementary School in Boise)

  9. Why aren't spiders a part of the insect family?

    Spiders and insects are very different. Spiders are essentially divided into two parts: a cephalothorax and an abdomen. Insects are divided into three parts: the head, thorax and abdomen. Normally insects will have six legs, and spiders have eight legs. The body part separation is probably the main difference. (From Adrianna at Cynthia Mann Elementary School in Boise)

  10. Why do mosquitoes suck blood?

    Only the female mosquitoes suck blood. The males have mouth parts but they feed on sweet things like nectar or fruit juices. For the females, blood is needed to nourish their eggs. (From Christopher at Sherman Elementary School in Nampa)