What is an insect?

Insects are animals that have roamed the earth for at least 300 million years, so they have been around way before dinosaurs.   Dinosaurs are extinct, but insects are still with us and some have changed very little since the days of the dinosaurs.    

With over 1,000,000 different kinds, insects have the honor of being the most numerous of all life forms on earth, and if you go out looking for them, they can be found almost everywhere.  

Insects are related to other common creatures such as crabs, crayfish, spiders, millipedes, centipedes and scorpions.  All of these animals are in a special group called the phylum Arthropoda (which means “jointed foot”). 

Even though insects and other arthropods, such as lobsters, do not look alike, all arthropods share the following characteristics: 

  1. A segmented body…much like a worm but with special groups of segments called “tagmata”
  2. Paired segmented appendages (legs)
  3. Bilateral symmetry (the right and left half look the same)
  4. An external skeleton that is molted as the animal grows

What makes insects different than spiders, crabs and scorpions?

what is an insect
For more details about insect anatomical characteristics, visit the Basic Insect Morphology page.

Where Can Insects be Found? 

Insect can be found almost everywhere on planet earth, even in the Artic.   Most live on land, but some live in fresh water, and a few can be found living in the oceans.  On land insects can be found high up on trees, or active deep in the soil, flying day and night, or crawling on the ground.    

Why are Insects so Successful?  

There are reasons why insects have been around so long and why there are so many different kinds.   Insects owe much of their success to the following: 

  1. Most insects have wings.   Wings have helped insects move around.   So when food becomes hard to find in one area, they can fly to another place with food.
  2. Adaptations.   There a many ways that insects have changed their behavior or body in some way to live indifferent habitats and feed on different plants or animals.   These changes include different kinds of legs, antennae, and mouthparts.  
  3. Eat about anything.   Insects will feed many things that we would expect them to, like plants in our gardens.   But some will feed on things that we would think are inedible, such as wood.   Some insects feed on a lot of different things, such as plants, while other may only eat a certain type of plant.
  4. Large reproductive capacity.   Most insects can have a lot of babies.   This helps adaptations to occur and increases survival.    There are some termite queens that can lay 30,000 eggs per day, and the queens may live for 10 years.