Phasmids
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.
A female spiny leaf insect which resembles a dried leaf.
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 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 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.
Head and mouth of a spiny leaf insect
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.
The female spiny leaf insect can curl up her abdomen to help 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.
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.
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
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.
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
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.
Seed-like spiny leaf insect eggs. The shape and colour of a phasmid egg is different for each species.
Phasmids digital book
Find out more
The Phasmids digital book explores the incredible features, adaptations and life cycles of Australian stick and leaf insects.
Learn about phasmids through detailed text, interactive activities, videos and stunning images.
This book supports Australian Curriculum biological sciences, living world and class studies on invertebrates.
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.