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Insects and Arthropods

Did you know we share our planet with over 1 million species of insects? That’s a lot of bugs! Scientists are discovering more insects every day. Insects are also called arthropods. Some have wings, and some don’t. But all have a few things in common.

Insects are a class of invertebrates characterized by a three-part body, three pairs of jointed legs, compound eyes, and wings (in most species). They are the most diverse group of animals on Earth, with over one million described species.

Insects play important roles in ecosystems as pollinators, decomposers, and food sources for other animals. However, some species can also be pests and transmit diseases to humans and other animals.

Insect Facts for Kids

  • Insects have six legs, but spiders have eight.
  • Butterflies taste food with their feet.
  • Ladybugs can eat up to 50 aphids a day.
  • Ants don’t have ears; they hear with their knees.
  • Bees are great dancers; they wiggle to communicate.
  • Caterpillars have about 4,000 muscles, humans have 600.
  • There are more types of beetles than any other insect.
  • Fireflies light up to find a mate.
  • Dragonflies can fly up to 35 miles per hour.
  • A mosquito has 47 teeth, but they don’t chew food.
Life Cycle of an Insect Image - Science for Kids All About Insects
All insects go through the same life cycle. Life begins as an egg. An adult insect emerges from the pupa.


Entomology is the study of insects. These creatures are everywhere on Earth and are the most abundant group of animals. Entomologists, the insect scientists, investigate how insects live, behave, and evolve. This research helps us understand the vital roles insects play, such as plant pollination. It also helps tackle challenges like diseases caused by insects and harmful pests.


Insects are part of the arthropod family, which also includes creatures like spiders and crustaceans. All arthropods have exoskeletons and jointed bodies. What makes insects unique in this family is their three-part body: a head, thorax, and abdomen, along with six legs. They are a successful evolutionary branch of arthropods, found in nearly every habitat on Earth.

Insect Biodiversity

Insects are incredibly diverse, with over a million known species, and they can be found in nearly every habitat on Earth. This biodiversity is due to their adaptability and reflects their importance in ecosystems. They help with crucial processes like pollination and decomposition, and are a food source for other species. The diversity of insects is vital for the health of our planet.

Insect Behavior

Insects show a range of complex behaviors. Bees communicate food locations with dances. Ants live in organized social groups with different roles. Some insects use camouflage for protection, and certain moths can interfere with bat sonar for defense. These behaviors, evolving over millions of years, show the adaptability of insects.

Insect Ecology

Insect ecology is about how insects interact with their environment and other organisms. They play key roles, like pollinating plants and decomposing waste, which helps keep our ecosystems balanced. They are also important food sources for other animals. Their presence can indicate the health of an ecosystem. Understanding this is crucial for conservation.

Insect Physiology

Insect physiology is about the structure and functions of insects. They have a protective exoskeleton and bodies divided into a head, thorax, and abdomen. The head has eyes and antennae, the thorax has wings and legs, and the abdomen contains internal organs. They breathe through tiny tubes called tracheae. Despite their small size, insects have complex systems that let them adapt to various environments.

Insect Evolution

Insect evolution dates back over 385 million years. Over time, insects developed wings and metamorphosis, which helped them adapt and diversify. Their evolution was also influenced by their relationship with flowering plants, especially for pollinators like bees. Studying this helps us understand biodiversity and adaptation.


Insects are crucial in pollination, which helps plants reproduce. They transfer pollen between flowers while looking for food. Bees, butterflies, beetles, and flies are all important pollinators. About 75% of flowering plants depend on these insects. Without them, our landscapes and food systems would change greatly.

Largest Insects

When considering the largest insects, different dimensions come into play: body length, wingspan, and mass. The longest insects are the stick insects, with the record held by Phobaeticus chani, known as Chan’s megastick, which can reach over 22 inches in total length when counting its extended legs.

The insect with the largest wingspan is the white witch moth (Thysania agrippina), with a wingspan reaching up to 12 inches. The heaviest insects are typically beetles. The Goliath beetles (Goliathus) can weigh up to 3.5 ounces in the larval stage. Despite these giants, most insects are much smaller, highlighting the remarkable diversity within the insect world.

Body Temperature

Insects are ectothermic, meaning their body temperature is affected by their surroundings. They don’t generate internal heat, but their behavior and survival depend on environmental temperatures. Some, like honeybees, can generate heat by shivering. Despite their lack of internal temperature control, insects can adapt to different temperature conditions.

Body Weight

Body weight in insects varies greatly due to the immense diversity of species. The smallest insects, like the fairyfly wasps, weigh only a few micrograms. On the other end of the scale, certain species of beetles and large moths can weigh up to a few grams.

For instance, the Goliath beetle in its larval stage can weigh up to 100 grams (around 3.5 ounces). This variation in body weight reflects the incredible range of adaptations insects have made to different habitats and ecological roles. For example, the lightweight structure of many flying insects enhances their mobility, while a heavier body weight can offer advantages in certain ground-dwelling species. Insects are truly a marvel of evolutionary design in terms of size and weight.

Fun Facts about Insects for Kids

  • Insects don’t have bones or a backbone like us. They’re called invertebrates. That means they have a hard exoskeleton, or shell, on the outside of their bodies that protects them.
  • All insects have three parts: the head, the thorax, which is the middle part, and the abdomen, or end part.
  • Insects have two antennae. They also have six legs.
  • Spiders are not insects. Spiders have eight legs. They are related to scorpions and belong to the arachnid family.
  • All insects hatch from eggs. The babies are called larva.
  • All insects go through the same life cycle. Life begins as an egg. The egg hatches and larva emerge. Larvae usually look nothing like the adult insect. The larvae enter a pupa, chrysalis or cocoon. An adult insect emerges from the pupa.
Body Parts of an Insect Image
All insects have three parts: the head, the thorax, which is the middle part, and the abdomen, or end part.

Insect Vocabulary

  1. Scientist: someone who studies science
  2. Arthropods: insects
  3. Invertebrate: an animal without a backbone
  4. Exoskeleton: a hard shell on the outside of the body
  5. Antennae: hair-like appendages
Insect Antennae Image
All insects have two antennae.

Learn More All About Insects

Check out this awesome video about how insects in the animal kingdom interconnect:

A video documentary all about insects and their lives.

Insect Q&A

How many insects live on the planet?

Insects make up over 90 percent of the animal life living on earth.

What’s an Anthropod?

Actually there’s no Anthropod insect. Anthropoids are actually something that is similar to the shape of a man, like a chimp. Some various extinct kangaroo species were called Anthropoids, as are also some non-living things such as machines or artworks.

What is an Arthropod?

Arthropods are invertebrate animals with segmented bodies, jointed limbs (legs) and cuticles. Spiders, insects, crabs and so forth are all arthropods. Their rigid cuticle inhibits growth, so arthropods replace it periodically by moulting.

How large is an Arthropod?

Arthropods range in size – from microscopic plankton up to a few meters long.

How many insects are Arthropoids?

Actually, all insects arthropods but not all arthropods are insects…

Are insects helpful?

Some insects, such as bees, help humans by pollinating crops. Others, like mosquitoes or fruit flies, can carry disease or damage crops.