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Insects (Insecta Group)

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There are more insects on Earth than all other kinds of creatures combined – over 900,000 known species. They are animals in the big group (or Phylum) Arthropoda, which includes crabs, spiders, scorpions and centipedes. Their group (or Class) is called Insecta has many smaller groups (Orders) that break insects down into like insects, like: beetles (Coleoptera), butterflies and moths (Lepidoptera) and grasshoppers (Orthoptera). for a list of insect orders: LINK

Classification of Insects:
Kingdom: Animals
Phylum: Arthropda
Orders: Orthoptera (Grasshoppers and Kaydids)

The study of insects is called entomology.

Insect Pests: Insects can hurt people by damaging food crops and forest trees, spreading diseases like malaria and yellow fever, or just biting and stinging painfully. Examples of insect pests are mosquitoes, caterpillars and fire ants.

Insect Helpers: Insects can also help people by pollinating food crops, making products like honey, supplying animals with food (like song birds, turtles, frogs and bats) and ridding us of other pests like aphids and such. Examples of helpful or beneficial insects are honey bees, praying mantis, and predatory ladybugs.

Looking at Insects: It is fun to collect insects that you find (that are already dead) and study them. Or just see insects outside and watch what they do. To understand insects and make watching them more interesting, there are some things you should know about them.

What Makes a Bug an Insect?

  • 3 body parts; a head, thorax and abdomen
  • 1-2 pairs of wings attached to the thorax
  • 3 pairs of legs attached to the thorax
  • 1 pair of antennae attached to the head
  • Mouth parts that bite, suck, pierce, lap, sip or rasp.



Insect diagram

Creatures that are NOT Insects: Some things may be "bugs," but are not true insects. These include spiders, millipedes and centipedes – who are in a bigger group (called a Phylum) with insects called Arthropoda. Other animal groups in Arthropoda are crabs, lobsters, scorpions, and barnacles.

Look for the insect traits you have learned to decide whether or not a bug is really an insect:

Is it an Insect? Illustration

Other Important Insect Traits
A good sample insect is the grasshopper. It has all the traits of a typical insect plus some other interesting features.

  • They listen with a type of eardrum on its sides.
  • They have grinding mouthparts for eating grass and a grinding gizzard to further breakdown its food.
  • They have small openings all over the body called spiracles through which they breathe.
  • They go through what is called "Incomplete Metamorphosis which means that they hatch out looking somewhat like an adult but smaller (this is called an instar) and gradually shed their hard outer layer (exoskeleton) as they grow (several times) into the adult size and form.

Other Insects, like butterflies and moths, go though "Complete Metamorphosis where they go through a complete change from birth to adulthood.

  • A butterfly hatches as a caterpillar (wormlike larvae) with mouthparts for eating.
  • Then it cocoons themself up to form a pupa, where it goes through a complete physical change.
  • Then it emerges from the cocoon or chrysalis as an adult insect.

One purpose of this change allows the insect to use several food sources. Early on as a caterpillar, it can eat leaves. Then by the time the adult butterfly emerges, the plants have flowered and they can collect nectar. They can also survive the winter in their pupal phase and try again next summer, though Monarch butterflies will actually migrate, flying all the way to Mexico for the winter months.

Insect metamorphosis Diagram


Assess Insect Parts - Fill in the Blanks.

Assess Insect Traits Multiple Choice Test for content comprehension: Mutiple Choice Test.

Assess Insect Traits True False Quiz for content comprehension: Quiz

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