Insects

Insects, Mantis, AustraliaInsects, pests, creepy crawlies, whatever you like to call them, are very much a part of our daily life, whether we like it or not. They generally keep to themselves and go unnoticed , until of course they get in our way or in our food.

We find them in the garden, in our houses, in the fields, under rocks, in our ponds and sometimes on us !  Sometimes we fear them, sometimes we like them and sometimes we kill them. Generally they are misunderstood.

Insects have been on this earth since the early Devonian period, which was some 400 million years ago, long before dinosaurs and humans existed ! Lots of things were happening in this period, fish were emerging and so too, seed bearing plants.

Sand Wasp, AustraliaSome scientists believe the first insects to evolve were from centipede-like creatures which began appearing on earth in the Silurian Period . However it wasn't really until the Cretaceous Period (145 million years ago) , that things began looking up for the insect. This was the period of the flowering plant and many new insect species began to emerge to take advantage of the forests and the newly established pollen producing vegetation. It didn't take long for insects to begin adapting to the changing environment. One of the most significant developments for insects at this time, was the ability to fly. This enabled the small creatures, especially bees, to move freely from flower to flower and inevitably spread pollen over greater distances.

What Is An Insect ?

An insect belongs to the group of animals known as arthropods. Arthropod is derived from the Greek word arthropoda, meaning "jointed legs". This group also includes crabs, centipedes, scorpions, spiders and worms.

An insect is an invertebrate (like all Arthropods) which means it does not have a backbone. Instead it has an exoskeleton which is a tough outer skeleton encasing the insect's body. The exoskeleton or cuticle is made from material known as chitin. The unique feature of chitin is it is extremely light in weight yet incrediable strong. Unfortunately the exoskeleon is not very flexiable and cannot grow, so in order for an insect to mature it must shed or moult it's body at various stages of it's life to become an adult. In fact all arthropods must shed their skin. But not to fear, the exoskeleton  is replaced by a new and larger one each time. Some lucky insects may only moult twice in their lifespan whilst others, less fortunate,  may moult over 25 times.  

The main characteristic which sets the insect apart from other arthropods, is it is the only group which possesses wings.  The insect body is divided into three parts, the head, thorax and abdomen. The head features the brain,  one pair of compound eyes, simple eyes (up to three), one pair of antennae and mouthparts such as mandibles and pincers. The thorax is made up of three segments, each segment carries one pair of jointed legs. When an insect has reached adulthood the second and/or third segments of the thorax carry the wings. The abdomen on the insect can consist of up to 11 segments and is generally where the sting , ovipositor and sensory organs can be found. For little creatures they can sure fit a lot onto their bodies.

Classifying Insects

One way that zoologists and taxonomists can identify animals is by classifying them into groups. This is done by placing animals into different groups depending on common features and characteristics. Starting with the Kingdom the group reads as follows phylum, class, order, family, genus and finally species.