Insects and Entomology

Entomology is the scientific study of insects, the most numerous and diverse group of animals on Earth. Insects belong to the class Insecta within the phylum Arthropoda, a vast group of invertebrates whose members share a hardened external skeleton, a segmented body and jointed limbs. What sets insects apart from other arthropods is a body divided into three distinct regions — head, thorax and abdomen — together with three pairs of legs, usually one or two pairs of wings, and a single pair of antennae.

More than a million insect species have been described, and the true total is thought to be many times higher. They are grouped into orders that reflect shared anatomy and development. Beetles form the order Coleoptera, the largest of all; butterflies and moths belong to Lepidoptera; flies to Diptera; and bees, wasps and ants to Hymenoptera. Smaller and less familiar orders include the earwigs. Many insects pass through a complete metamorphosis, transforming from egg to larva to pupa to adult, while others change more gradually.

Insects are ecologically essential. Bees, butterflies and other insects pollinate a large share of flowering plants, including many food crops, while others decompose dead material, aerate soil, or serve as food for birds, reptiles and mammals. Some are agricultural pests or carriers of disease, which makes entomology important to farming and public health as well as to basic biology.

Frequently asked questions

What makes an insect an insect?

An insect has a body in three parts (head, thorax, abdomen), six legs, a pair of antennae, and usually wings. These features distinguish it from spiders and other arthropods.

What is entomology?

Entomology is the branch of zoology devoted to the study of insects, including their classification, anatomy, behaviour and ecology.

Are insects arthropods?

Yes. Insects form the class Insecta within the phylum Arthropoda, which also includes spiders, crustaceans and other jointed-legged invertebrates.