Insect Glossary

Abdomen: The last of the three segments of an insect’s body. The abdomen is at the rear end of the insect and contains the digestive, reproductive & nervous systems.

Antennae: A pair of sensory structures found on the insect’s head that are used to sense touch, air movement and chemical smells.

Arthropod: This assemblage of animals includes spiders, scorpions, millipedes, centipedes, insects and crustaceans. Arthropods are distinguished from other animals by having a hard outer exoskeleton and jointed legs.

Camouflage: A technique for avoiding your enemies by hiding or blending into your surroundings. Insects often look like leaves, sticks and rocks to aid in their camouflage.

Caste: Individuals of a colony of social insects that differ from other members of the nest, either by their age, appearance or jobs. For example, in termite colonies the soldier caste differs from the workers by having large heads, strong mandibles and larger, stronger bodies for defending the nest.

Cephalothorax: The first of the two segments of a spider’s body. The head and thorax fuses in arachnids to form the cephalothorax.

Cerci: A pair of sensory structures found at the end of the abdomen in some insects. Cockroaches have well developed cerci to detect the air currents of approaching enemies. (which is why you can never sneak up on one and try & squash it)!

Chrysalis: The name given to a butterfly pupa.

Cocoon: A protective case woven from silk by the larva. Inside the cocoon the larva will turn into a pupa.

Colony: Many individuals of a single species of insect, living & cooperating together.

Complete Metamorphosis: see Holometabolous Lifecycle.

Compound eyes: A pair of visual organs found on an insect’s head. Each compound eye is made up of many (up to several thousand) little lenses that join together to form the eye.

Cuticle: A slippery or waxy layer covering the exoskeleton. It helps to keep the insect’s shell waterproof. In cockroaches the cuticle is very slippery and helps them to wriggle into cracks and crevices to escape enemies.

Diurnal: Most active during the daytime. For example, most butterflies are diurnal as they fly during the day and rest at night.

Entomologist: A scientist who studies insects.

Exoskeleton: The hard outer shell that covers an insect’s body.

Eyespots: Circular markings on the bodies of insects that look like a giant pair of eyes. This can help insects trick their enemies into thinking they’ re a much larger animal.

Fangs: The hollow piercing part of a spider’s jaws which are used to deliver venom and suck the juices out of their prey.

Gradual Metamorphosis: see Hemimetabolous Lifecycle

Head: The first segment of an insect’s body. The head is at the front of the body and bears the eyes, antennae and mouthparts.

Hemimetabolous Lifecycle: An incomplete form of metamorphosis where the newly hatched insect resembles the adult and simply grows larger with each successive moult. There is no larval or pupal stage in this kind of lifecycle. Also known as Simple or Gradual Metamorphosis it is used by more primitive insects such as stick insects, preying mantids, cockroaches, cicadas and dragonflies.

Holometabolous Lifecycle: A complete form of metamorphosis where the insect passes through four distinct stages – the egg, larva, pupa and adult. For this lifecycle, the hatchling insect looks like a grub or caterpillar and does not resemble the adult at all. Modern insects such as butterflies, beetles, bees, wasps and ants use this lifecycle.

Honeydew: A sweet liquid produced by many true bugs such as aphids.

Instar: The stage of an insect’s life between moults of the exoskeleton. For example the first instar is the time between hatching out of the egg and the first time the insect will shed its skin.

Invertebrate: An organism that has no backbone (i.e. spine).

Mandibles: The hard jaws of an insect used for biting and grinding food.

Metamorphosis: The process by which a nymph or larva changes into an adult. In other words, metamorphosis sums up the changes that happen to an insect throughout its life.

Mimicry: Pretending to be something else to avoid getting eaten by a predator. Some insects and spiders are brown and white to mimic bird droppings (not very appetising to a predator). Others mimic sticks, leaves and rocks to aid in their camouflage.

Moulting: The process by which insects peel off their exoskeletons to reveal a new, larger shell underneath (much like a snake shedding its skin). This enables the insect to grow larger.

Nocturnal: Most active during the night. For example most moths are nocturnal as they fly at night and rest during the day.

Nymph: The name given to the immature stage of an insect that undergoes a hemimetabolous lifecycle.

Ovipositor: A special tube used for laying eggs, located at the end of the female’s abdomen.

Pheromone: A chemical smell produced by insects to communicate with each other.

Proboscis: A long, drinking straw-like tube used for sucking up liquids such as nectar. Usually seen on butterflies and moths.

Prolegs: The suction cup-like pads found on many caterpillars that helps it grip onto the plant. Many people mistake these for legs.

Pupa: The third stage (between the larval and the adult stage) in the lifecycle of a holometabolous insect. During this inactive phase the insect transforms into an adult.

Segment: The name given to a section of an insect’s body.

Setae: Special hairs on the body of an insect that can be used to smell, taste, touch or hear.

Simple Metamorphosis: see Hemimetabolous Lifecycle

Social Insects: Insects that live together with other members of their species in a nest or colony.

Solitary Insects: Insect that are not social (i.e. they live alone).

Spiracle: A special hole usually on the side of an insect’s abdomen that is used for breathing.

Stridulation: The funny squeaking sound a rhinoceros beetle makes when you pick it up. Many insects stridulate by rubbing certain parts of their bodies together.

Thanotosis: This means playing dead. Some insects drop to the ground and pretend to be dead to avoid getting eaten by predators (who prefer to eat fresh food and not something that is already dead).

Thorax: The middle segment of an insect’s body, found between the head and the abdomen. The legs and wings grow from here and the thorax contains the muscles needed to operate these limbs.