Phasmids fact sheet

What are phasmids?

Phasmids are a group of insects from the Phasmatodea order. They are commonly known as stick and leaf insects. They are very well-camouflaged and can be found living on most Australian native plants including trees, shrubs and grasses.

Australia is home to around 150 species of phasmids. Worldwide there are over 3000 species. Some Australian phasmids include spiny leaf insects, strong stick insects, goliath stick insects and spur-legged leaf insects.

Illustration of a female spiny leaf insect with a flat, leaf-shaped body that looks like a dried leaf. A female spiny leaf insect which resembles a dried leaf.

Fast facts – Phasmids

What are they – Phasmids are insects in the order Phasmatodea, commonly called stick and leaf insects.

Body features – Many species look like a stick or a leaf. Male phasmids are usually smaller than females, with longer antennae, large wings and the ability to fly. Female phasmids are larger and heavier, with small wings and cannot fly.

Diet – Phasmids are herbivores – they eat plants. Most eat leaves from a range of plants such as eucalyptus and lilly pilly trees.

Where they live – They are very well camouflaged and live on many Australian native plants, including trees, shrubs and grasses.

Life cycle – Many species lay one egg at a time and flick the abdomen to catapult the egg into the forest; some stick their eggs to the underside of leaves. They grow through incomplete metamorphosis – the young resemble adults, and each time they moult their body looks more like an adult.

Stick insect with a long smooth brown body and legs that resemble a twig on a branch. The strong stick insect is camouflaged to help it look like a stick.

What is the appearance of male and female phasmids?

Male phasmids are usually smaller than females. They have longer antennae, large wings and can fly. In comparison, females are larger, heavier, have tiny wings and cannot fly.

Male spiny leaf insect with a narrow body and large outspread wings ready to fly. 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 phasmids eat leaves from a variety of plants such as eucalyptus and lilly pilly trees. Some phasmids are very fussy and will only eat one type of plant.

Goliath stick insect hanging upside down while chewing along the edge of a eucalyptus leaf. Goliath stick insect feeding on a eucalypt leaf

How are phasmids adapted to their environment?

Phasmids are well camouflaged and usually look like a part of a plant. For instance, spiny leaf insects look like dried-up dead leaves. They often sway from side to side when hanging, like a leaf moving in the wind.

Phasmids have curved claws for hanging upside down and moving amongst branches. They have a vertical mouth for feeding on leaves, chewing along the edges.

Some phasmids have small spines on their bodies to detract predators.

Close-up of a spiny leaf insect’s head showing antennae, eyes and vertical chewing mouthparts. Head and mouth of a spiny leaf insect

Close-up of a spiny leaf insect leg with two curved claws used to grip branches. Spiny leaf insects have two strong claws at the end of each leg.

Reproduction

Female phasmids can produce eggs without a male. This form of reproduction is known as parthenogenesis and results in all the eggs hatching into females.

Eggs fertilised by males hatch into both males and females.

Phasmids can lay thousands of eggs in their lifetime. They lay one egg at a time and flick their abdomen to catapult the egg into the forest. Some will stick their eggs to the underside of leaves.

Female spiny leaf insect curling the tip of her abdomen to flick an egg towards the forest floor. This young female spiny leaf insect can curl up her abdomen. Once an adult she will throw eggs down to the forest floor.

Phasmid life cycle

All phasmids begin their life cycle as an egg. Phasmids grow through a process called 'incomplete metamorphosis' which means the young resemble adults. Each time they moult their body changes to look more like an adult.

Each stage of growth between moults is called an instar. Most phasmids have 5 or 6 instar stages before they become an adult.

https://players.brightcove.net/6129823267001/default_default/index.html?videoId=6270561445001

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

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.

Close-up of a round spiny leaf insect egg that looks like a small brown seed on the forest floor. Spiny leaf insect egg

Nymph

Baby phasmids are called nymphs. They are small and fast. Many phasmid nymphs look like large ants.

Spiny leaf insect nymph that looks like a large brown ant walking on a plant. Spiny leaf insect nymph

Instar

To grow or change shape phasmids shed their exoskeleton. Each stage of growth between moults is called an instar. Most phasmids have 5 or 6 instar stages before they become an adult.

Pale empty exoskeleton of a spiny leaf insect left behind after moulting. A recently shed exoskeleton of a spiny leaf insect

Adult

Most female phasmids can live for 18 months. Males have a much shorter lifespan of only 6 to 8 months.

Adult female spiny leaf insect with a large leaf-shaped body and six spiny legs on a branch. Adult female spiny leaf insect

What role do phasmids play in the environment?

Many phasmid eggs look similar to seeds and have a bump on top called a capitulum. Some large ants carry phasmid eggs to their underground nest to store for food. The ants eat the oily capitulum but do not harm the eggs. Whilst underground the eggs stay safe from predators. Once the nymph hatches it leaves the nest to find a tree.

Phasmid droppings help fertilise the soil. They are food for vertebrate animals such as birds and lizards.

Cluster of round spiny leaf insect eggs, each with a small lump at one end, resembling tiny seeds. Seed-like spiny leaf insect eggs. The shape and colour of a phasmid egg is different for each species.

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

The life stages of a phasmid video transcript

Video transcript

Hi we're at the Field of Mars Reserve and we're going to learn about how animals change as they grow.

This is a spiny leaf insect. She's a type of phasmid.

She has a really fascinating life cycle.

Adult female phasmids release their eggs onto the forest floor which are collected by ants and taken underground to their nests.

Baby phasmids which are called nymphs will emerge from their eggs and leave the ant nest where they will then climb up the nearest tree and begin to feed on leaves.

Over their life cycle phasmids will moult and shed their exoskeleton several times before they reach their full size.

The adult phasmid will then spend the rest of its life living in the trees and feeding on the leaves.

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