Phasmid fact sheet | Field of Mars EEC

What are phasmids?

Phasmids are insects in the order Phasmatodea. They are commonly called stick insects or leaf insects because many species look like sticks, leaves, bark or grass.

Phasmids are masters of camouflage. They can be very difficult to spot because their body shape, colour and behaviour help them blend in with the plants they live on.

Australia is home to about 150 species of phasmids. Some Australian phasmids include spiny leaf insects, strong stick insects, Goliath stick insects and spur-legged leaf insects.

A female spiny leaf insect.

The strong stick insect is camouflaged to help it look like a stick.

Where do phasmids live?

Phasmids live in places where they can find suitable food plants and shelter. Many species live in trees and shrubs, while others may be found in grasses or leaf litter.

They are often found on eucalypts and other native plants. Some species may also appear in gardens on plants such as rose bushes or fruit trees.

At Field of Mars Reserve, phasmids may live among native trees, shrubs and leaf litter. Their camouflage makes them easy to miss, even when they are close by.

A stick insect camouflaged among eucalypt leaves.

What do phasmids look like?

Phasmids vary in size, shape and colour. Many are brown or green, which helps them blend in with leaves, twigs and branches. Some have spines, leaf-like lobes or long thin bodies.

Male and female phasmids can look very different. In some species, males are smaller, slimmer and have larger wings that help them fly. Females are often larger and heavier, with smaller wings or no useful wings for flying.

Male spiny leaf insects have large retractable wings to them escape from predators and to find a mate.

What do phasmids eat?

Phasmids are herbivores, which means they eat plants. Most feed on leaves, especially from trees and shrubs.

Some species eat a range of plants, while others prefer only a few food plants. Many Australian phasmids feed on eucalypt leaves. Some species kept in classrooms or homes may also eat leaves from plants such as lilly pilly, rose or raspberry.

As phasmids feed, they chew leaf edges with their mouthparts. Their droppings, called frass, return nutrients to the soil.

Goliath stick insect feeding on a eucalypt leaf.

What is the life cycle of a phasmid?

Phasmids grow through incomplete metamorphosis. This means they do not have a caterpillar or pupa stage. Instead, their life cycle has three main stages: egg, nymph and adult.

A female phasmid lays eggs. Some species drop or flick their eggs to the ground, while others attach eggs to leaves or plants. Many phasmid eggs look like small seeds in the leaf litter.

A young phasmid is called a nymph. Nymphs look like smaller versions of adults. As a nymph grows, it sheds its hard outer covering, called an exoskeleton. This process is called moulting. Each stage between moults is called an instar.

After several moults, the phasmid becomes an adult. Adult females can lay eggs and begin the life cycle again.

Egg

All phasmids lay eggs. The eggs are camouflaged to blend in with the leaf litter on the forest floor, looking like seeds. The eggs can take one to 2 years to hatch.

A spiny leaf insect egg looks like a small seed.

Nymph

Baby phasmids are called nymphs. Some nymphs are small, fast and may look like ants when they first hatch. This can help them move through the leaf litter safely.

A spiny leaf insect nymph can look like a large ant when it first hatches.

Instar

To grow, a phasmid must moult. During moulting, it sheds its old exoskeleton. Each growth stage between moults is called an instar.

A recently shed exoskeleton left behind after moulting.

Adult

Adult phasmids are fully grown. Adult females are often larger than males and may live longer. In some species, males are smaller and can fly.

An adult female spiny leaf insect.

The life stages of a phasmid |  YouTube  | Field of Mars EEC (1:04 min)

How do phasmids reproduce?

Many female phasmids can produce fertile eggs without mating. This is called parthenogenesis. Eggs produced this way usually hatch into female nymphs.

When a female mates with a male, the eggs may hatch into male or female nymphs. This helps keep variety in the population.

Some female phasmids lay many eggs during their adult life. Instead of caring for their young, they spread their eggs into the environment. This gives at least some eggs a chance to survive.

This young female spiny leaf insect can curl up her abdomen. Once an adult she will throw eggs down to the forest floor.

What adaptations do phasmids have to help them survive?

Phasmids have body shapes and colours that help them blend in with plants. Stick insects may look like twigs, while leaf insects and spiny leaf insects may look like dried or living leaves.

Many phasmids stay very still when threatened. Some sway from side to side, like a leaf or twig moving in the wind. Others drop to the ground and remain motionless like a fallen stick.

Their legs have claws that help them grip leaves, stems and branches. Some phasmids have spines or hard body parts that make them harder for predators to eat. Some males can fly away, while some species use sudden wing movements to startle predators.

Phasmid eggs can also help them survive. In some species, eggs look like seeds and have a small knob called a capitulum. Ants may carry these eggs underground, eat the capitulum and leave the egg safely inside the nest.

A close-up view of a spiny leaf insect’s head and chewing mouthparts.

Spiny leaf insects have two strong claws at the end of each leg.

Why are phasmids important?

Phasmids are part of the bushland food web. They provide food for animals such as birds, reptiles, spiders and predatory insects.

They also help return nutrients to the soil. As phasmids eat leaves, their droppings fall to the ground and break down in the leaf litter.

Some phasmids have an important relationship with ants. Ants may carry seed-like phasmid eggs into their nests. The ants get food from the small capitulum on the egg, while the egg may be protected underground until the nymph hatches.

Seed-like spiny leaf insect eggs. The shape and colour of a phasmid egg is different for each species.

How can you help phasmids?

You can help phasmids by protecting habitat. Keep native trees, shrubs, grasses and leaf litter where it is safe to do so. These places provide food, shelter and camouflage.

Avoid unnecessary pesticide use, especially on plants where insects may be feeding or sheltering. Pesticides can harm phasmids and many other small animals.

If you find a phasmid, observe it gently and leave it where it is. Do not pull its legs or wings, as phasmids can be delicate. A quiet photo from a safe distance is the best way to record what you have found.

Fallen timber, shrubs and leaf litter can provide shelter and camouflage for phasmids.

Related fact sheets

More invertebrate fact sheets

• Invertebrate fact sheets – overview
• Insects fact sheet – general insect body parts and features (phasmids are insects).
• Bush cockroaches fact sheet – another group of plant-eating insects living in leaf litter and shrubs.
• Golden-tailed spiny ant fact sheet – connects to ants’ role in moving and protecting seed-like phasmid eggs.

Habitats and ecosystems

• Leaf litter habitat fact sheet
• Tree habitats fact sheet
• Field of Mars Reserve fact sheet

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