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.
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.
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.
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 verticle mouth for feeding on leaves, chewing along the edges.
Some phasmids have small spines on their bodies to detract predators.
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.
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 five or six instar stages before they become an adult.
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 capitumum 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.
