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Insect Species

Insects

Explore the largest group of animals on Earth. From butterflies to beetles, discover the incredible diversity of insects.
241 Species
17 Orders
1 At Risk
Featured Species

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Conservation Focus

Insects at Risk

1 insects in our database face conservation challenges. Learn about these species and what threatens their survival.

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Where They Live

Insect Habitats

Agricultural/Farmland 231 species
Suburban 227 species
Urban 225 species
Woodland 221 species
Plantation 188 species
Deciduous Forest 187 species

All insects are part of the taxonomical phylum Arthropoda, and they are collectively referred to as arthropods. It is common to see this name misspelled as “anthropod,” but this is not the correct term. They can be found in nearly every environment on the planet, and they currently account for over half of all known living organisms in the world.

They have undergone many cycles of evolution depending on the resources available to them. With over one million described species currently living, and millions more estimated to exist, insects greatly outnumber all other animals.

In general, this classification of creatures is referred to as Insecta. In some cases, the terms “Ectognatha” and “Entomida” may be used instead, but these three labels are synonymous and may be used interchangeably. For simplicity, this guide will always use the classification Insecta.

The name Insecta is derived from the Latin word “insectum,” which means “divided body” or “cut into sections.”

Learn about why insects are classified as animals here.

The Four Major Insect Characteristics Listed

Goldenrod Soldier Beetle

Insects are one of the most diverse groups on the planet

©Muskoka Stock Photos/Shutterstock.com

Insects are one of the most diverse groups on the planet, and their evolution throughout history is astounding. However, in order to be considered a member of the class Insecta, animals must meet a certain number of criteria. In fact, many people are surprised to learn that many of the bugs that are commonly believed to be insects are technically not a part of the Insecta class.

1. Insects have three distinct body segments.

One of the most well-known defining characteristics of insects is the division of their bodies

©Charles J. Sharp / CC BY-SA 3.0 – Original / License

One of the most well-known defining characteristics of insects is the division of their bodies into three sections: head, thorax, and abdomen. The head features a single pair of antennae and a pair of either simple or compound eyes.

This is also where the mouth is located, but the type of mouth is dependent on the type of insect. Mouth variation is one of the main factors used to classify insects.

The thorax is the midsection, and this is where the legs and wings are attached. The abdomen houses the digestive and reproductive organs, and it is also where the stinger is located if the insect has one.

2. Insects have six legs.

European bat bug

True insects only have six legs.

©iStock.com/Zdenek Macat

Unlike other members of the larger phylum Arthropoda which class Insecta belongs to, true insects only have six legs. Arachnids are often mistaken for insects, but they have eight legs. All insects have three pairs of jointed legs that are attached to the thorax of the body.

3. Insects have an exoskeleton.

Click Beetle Larvae

Click beetle larvae have elongated, slender, shiny bodies with hard exoskeletons.

©Henrik Larsson/Shutterstock.com

Insects are classified as invertebrates, which means they have no internal spinal column to provide structure and protection. Instead, they have what is known as an exoskeleton, which literally means “outer skeleton.” These external skeletons are made from a tough, inflexible material called chitin, and they provide the support and protection that would typically come from an internal skeleton.

4. Insects hatch from eggs.

Parasitic fly, Tachinid fly

Parasitic flies are known for their unique ability to lay eggs on other insects.

©iStock.com/Wirestock

Almost every known species of insect hatches from an egg. For insects, fertilization and development occur inside the egg, and the eggs of most species are specially designed to withstand harsh weather conditions such as droughts.

What Do Insects Eat?

Depending on the Species of insects, they eat plants, flowers, fruits, and other insects.

Many insects eat grass and leaves. Some other insects eat decaying food such as garbage or carcasses. Furthermore, there are other insects that only drink liquids such as butterflies, mosquitos, and bees. Many insects are attracted to sweet things such as honey, nectar, or sap.

Evolution and Origins

Class Exceptions

Cockroaches are ovoviviparous, which means that the eggs develop inside of the mother and hatch as soon as they are laid.

©D. Kucharski K. Kucharska/Shutterstock.com

As with most classification systems, there are a few exceptions to the general rules that govern which species are included in the class Insecta.

  • Certain species do not lay eggs.

    The majority of insects lay eggs that develop and hatch outside of the mother. However, there are a handful of insect species that reproduce via different methods, such as those listed below.
    • Juvenile aphids, tsetse flies, and certain cockroaches are ovoviviparous, which means that the eggs develop inside of the mother and hatch as soon as they are laid.
    • Other cockroach species are viviparous, so the young gestate inside of the mother and are born alive.
    • Some insect species display polyembryony, which means that one fertilized egg divides into many separate embryos.
  • A few species are bioluminescent.

    A small number of insects, such as fireflies, are able to generate light that can be used for mating or luring prey.
  • A select few insects are long-lived.

    In general, insects live short lives. While most insects may only live a few days or weeks, the egg-laying queens of some ant, bee, and wasp species can live for many decades.

The Life Cycle of Insects

Animals With The Shortest Lifespan

The life cycles of insects are divided into two basic groups: complete and incomplete metamorphosis.

©iStock.com/Niklas Toelle

The life cycles of insects are divided into two basic groups: complete and incomplete metamorphosis. Each life cycle has its advantages and disadvantages in terms of evolution.

Complete the Metamorphosis Steps Listed

Complete metamorphosis happens in four distinct stages.

  1. Egg: The female lays fertilized eggs that hatch after a given span of time.
  2. Larva: This is the growth phase. Larvae spend nearly all of their time eating in order to prepare for their final transformation.
  3. Pupa: The pupa is in the transformation phase. The insect is contained within a hard shell called a chrysalis, and all of the internal organs are broken down into a kind of “soup.” This liquefaction allows the adult body to form.
  4. Adult: Once the reorganization of the pupa stage is complete, the chrysalis will split open and the fully formed adult emerges.

Incomplete Metamorphosis Steps Listed

cockroach nymph on woodgrain background

As with insects that undergo complete metamorphosis, eggs are laid by the female and hatch into young known as nymphs.

©bamgraphy/Shutterstock.com

Incomplete metamorphosis occurs in lesser-developed insects and happens in only three stages.

  1. Egg: As with insects that undergo complete metamorphosis, eggs are laid by the female and hatch into young.
  2. Nymph: In this stage, the young look like miniature versions of adults, but they cannot reproduce. Wings develop during this stage rather than the pupal stage. Nymphs will undergo a series of molts in order to shed their inflexible exoskeletons as they grow.
  3. Adult: After a nymph’s final molt, it will have fully developed wings and the ability to reproduce.

Insect List

Complete Directory

All Insects by Order

Dermaptera 1

Earwig

Ephemeroptera 1

Mayfly

Isoptera 1

Termite

Mantodea 1

Praying Mantis

Meganisoptera 1

Meganeura

Odonata 1

Dragonfly

Siphonaptera 1

Flea

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