Insects are fascinating creatures and can be found everywhere on this planet. Our young explorers encounter this life form early on in their life. And I would like to share some interesting facts about these little creatures. Though insects have a short life span but their evolutionary records goes back to 400 million years ago. They live everywhere, be it air, water, land, hot weather, cold weather. Everywhere! We all know the tiny little hard working ants, right?
There are more than 800,000 different kinds of insects. They include butterflies and beetles, fleas and flies, crickets and chiggers. Although they come in almost every shape, most insects have a few things in common.
They have a body divided into three regions called head, thorax, and abdomen, have three pairs of legs mostly, and mouth parts located outside of the head capsule. Most insects have wings and can fly. Most insects also wear their skeletons outside their bodies as hard shells. And all insects begin as eggs.
Insects have a rigid body covering, called an exoskeleton, they are not able to increase in size by simply expanding. As the insect grows, the body covering is periodically shed and replaced with a larger one in a process called molting. Most insects molt several (4 to 8) times between emergence from the egg stage and when they become adults. Most insects do not molt as adults.
The term life cycle means the series of changes in the life of an organism including reproduction.
All organisms goes through various stages of the life cycle. Humans are born as fully formed beings. When we were born, our body was shaped a lot like it is now. It was smaller, of course and we grow mentally and physically but we still have ears, eyes, nose, arms or legs in all stages of our life. When we grow up, our body shape will be about the same. But some baby animals look nothing like the adults they will become.
Life cycle of an insect can be truly amazing where one stage of the organism looks entirely different from their adult stage of life. The stages can be not only structurally unrecognizable from an adult form but it can also be different in eating habits and behave like a different species in different forms of life. It can be hard to say that if it’s the same organism if we don’t study them.
Highly developed insects have a four-stage life cycle and show complete metamorphosis. The insect lives as
- the egg
- the larva
- the pupa (chrysalis)
- the adult
Others have a three-stage life cycle. The insect is born as
- the egg
- the nymph
- the adult
Most insects lay their eggs near the food they like to eat. Moths and butterflies lay eggs underneath leaves. Dung beetles lay eggs in balls of animal poop. Many flies lay eggs on meat. Some insects even lay eggs on other animals.
Many insects make special cases to protect their eggs. One insect puts foam around its eggs. Many lay eggs in pools, ponds, streams or underground. Rarely, a female insect keeps the eggs inside her body. The eggs hatch, and the young are born alive.
Most eggs hatch into a worm-like stage called a larva. Caterpillars, grubs, and maggots are larvae. They have long bodies and many legs. Larva is the growth phase. It is generally very different from the adult. Usually the larva and adult use different food sources. Almost all larvae are eating machines. A larva can eat more than its own body weight in one day.
Many larvae can destroy crops. They can suck sap from crop roots, eat leaves, fruits or vegetables. On the other hand, the silkworm, a moth larva, makes silk thread.
Once the larva has grown, it must totally change its shape. And it must protect itself while it does so. Pupa(or chrysalis) is a stage of internal reorganization and is also known as the “resting” stage. Many larvae spin cocoons out of silk or grow hard shells. The pupa does not eat and does not move much. There are no visible signs on the outside of the body as to the activity within. The insect is very busy changing shape. This change is called metamorphosis.
When reorganization is complete, the adult is ready to emerge. The pupa hatches and an adult insect with wings, six legs, and three body parts. Such a life cycle is shown by butterflies, moths, bees, wasps, true flies and many other insects, including beetles. Adult insects will find mates, and the females will lay eggs. Sometimes, this is all the adults do. Mayfly adults live for only one day. Most other insects have longer adult lives. They eat, fly, hunt, and work.
In the three-stage life cycle, eggs do not hatch as larvae. They hatch as nymphs, which look like small adults. Nymphs do not turn into pupae. Instead, they shed their skin as they grow. Each time they shed their skin, they look more like an adult. Slowly, the nymph transforms into an adult. This lifecycle can be seen in crickets, mayflies, dragonflies, termites, mantises and cockroaches.