Insects are the most successful type of creature on Earth. Indeed, as many as 1 out of every 4 species of life on our planet is some type of beetle. There are ~900,000 named species of insects in the world. More than 86,000 species live in North America, and an estimated 15,000+ of those may be found in Kansas.
All About Insects
- Are in Class Insecta within the Phylum Arthropoda.
- Have three body parts: head, thorax, and abdomen.
- Do not have bones! Instead they have an exoskeleton. The primary compound in the exoskeleton which gives it stiffness and strength is chitin.
- Have six legs.
- Have one or two pairs of wings as an adult (with some exceptions).
- Have one pair of antennae (singular: antenna) on the head.
- Have two compound eyes made up of many small simple eyes called ommatidia (singular: ommatidium). In addition, most insects have one to three simple eyes called ocelli (singular: ocellus).
- Transform as they grow through a process called metamorphosis.
With more than 15,000 insects thought to be found in Kansas, the list below is meant to be representative rather than comprehensive.
The most advanced types of insects go through four stages: egg, larva, pupa, and adult
This is called Complete Metamorphosis.
The larval stage does little except eat and grow. Larvae may be slow-moving like a worm or caterpillar or they may have be fairly active with well-developed feelers and legs. Ordinarily a larva has a constant appearance throughout its life, but a few species of insects (mainly certain beetles and flies) have more than one kind of larva! These are said to undergo hypermetamorphosis.
The pupa is a resting stage where the body of the insect is transformed into the adult. Usually a special outer covering is formed to protect the helpless creature at that time.
- Butterflies make a chrysalis.
- Some flies make a puparium.
- Moths use silk to spin a cocoon.
What emerges after pupation is something totally unlike the larva--the adult--with wings and a different body, legs, and mouthparts. Insects with complete metamorphosis include beetles, butterflies, moths, scorpionflies, fleas, true flies, caddisflies, thrips, lacewings, antlions, bees, wasps, and ants.
Many insects have a three stage metamorphosis: egg, nymph, and adult.
This is called Gradual or Incomplete Metamorphosis.
What hatches from the egg is a small version of the adult, except it lacks wings. These young nymphs live on the land (a few live in the water, but do not have gills) and molt as they grow.
The final molt reveals a creature with fully-developed wings--the adult.
Insects with incomplete metamorphosis include true bugs, roaches, cicadas, leafhoppers, lice, termites, mantids, earwigs, crickets, grasshoppers, and walking sticks.
Dragonflies, damselflies, stoneflies, and mayflies have incomplete metamorphosis, but the second stage is called a naiad. Naiads are aquatic and possess gills. They look like an insect, but are different from the adults. When finished growing, they emerge from the water and shed their skin to become an adult.
Mayflies also have the distinction of being the only type of insect that molts after becoming an adult! The first adult is called a subimago, which promptly molts again-- wings and all--and becomes the imago, or true adult.
The most primitive types of insects--springtails, bristletails, and silverfish--have no observable difference between young and adults. They are said to have no metamorphosis.