What does it look like?
Stick Insects are long, thin, slow moving insects that look like a stick or twig. They are also called walking sticks. Males tend to be smaller than females. Colors are usually brown or green, but may be grey or shades of red. Also shaded orange but in little places. Stripes, spots, and speckles are common. Males usually have wings, but females are often wingless. Short, tough forewings protect the large fan-shaped hind wings.
The common American Walking Stick is slender and shiny with long antennas. The adult male is 2 to 3 inches long with bands of color. The adult female is 3 to 4 inches long.
The New Guinea Spiny Stick Insect is big and bulky. It is 4-1/2 to 6 inches long. It resembles a branch more than a slender stick. Colors are dark brown to black. The legs are thick and prickly. Adult males have a long thorn on each hind leg. Nymphs are green-and-brown patterned.
The Two-striped Walking Stick is also known as Prairie Alligator and Devil’s Riding Horse. It is large and relatively stout with three longitudinal black stripes down its back.
Where can it be found?
Walking Sticks are found in North America, Australia, and around the Mediterranean Sea in Europe. They are abundant in the rainforests of Asia, Africa, and South America. They live in tropical areas and warm temperate regions. Their natural habitat is woodlands and forested areas where there are many broadleaf trees. They live on the foliage of shrubs and bushes and on tree stems.
Common American Walking Sticks can be found east of the Mississippi River, from southern Canada to central Florida. They are also found in parts of Arizona and northern Mexico.
Giant Spiny Walking Sticks live on the ground instead of trees or bushes. They hide under bark and stones during the day.
What does it eat?
Stick insects are herbivorous, eating only plants and vegetation. They eat berries, vines, and leaves. They feed at night.
Adult American Walking Sticks prefer to eat oak leaves. Nymphs feed on oak leaves and various plants, berries and shrubs that grow under the oaks. They also eat fabric textiles.
How does it defend itself?
Stick insects protect themselves by remaining motionless for hours. Sometimes, they gently sway back and forth like a small branch being blown by the wind. They hold their legs tightly along the body so they look like a stick or twig. The surrounding vegetation makes them almost invisible to predators. First-stage nymphs are tiny and have protective camouflage.
Other defense tactics include using unpleasant smells, noises, postures, protective coloration, and sharp spines on the legs.
Sometimes the undersides of the wings are brightly colored. When the stick insect senses danger, the wings will open very fast revealing a bright flash of color to scare away predators. Often, wings act as miniature parachutes. The stick insect can fall from a branch, unfold its wings, and glide to safety.
The Two-striped Walking Stick has bright stripes that act as warning coloration. It is also called “musk mare” because it squirts a strong-smelling defensive spray when threatened.
What stages of metamorphosis does it go through?
A Stick Insect undergoes incomplete metamorphosis, changing from egg to nymph to adult. There is no pupal stage. The female deposits eggs through a special tube (ovipositor) at the tip of the abdomen.
In a few species, the female lays eggs by hanging upside down from a branch. She arches her abdomen then straightens up and flicks the eggs away. The eggs are thrown some distance and scattered over a wide area. In the spring nymphs emerge from a tiny cap at one end of the egg.
About two weeks after mating, the female flicks, drops, or scatters her eggs. Some species take care to protect their eggs. They bury their eggs in the ground or hide them in the bark of a tree. Often eggs are attached to leaves or branches by a special sticky substance. Some eggs look like seeds, and ants take them to their nests where they are protected.
To grow bigger the nymph molts, growing a new skeleton under the old one. The old skin cracks open and the nymph emerges with a new cover. The new outer casing is soft at first, and the nymph must be careful to avoid danger until it hardens.
Finally, after several molts, the nymph becomes an adult. The average lifespan of a Walking Stick is 1 to 2 two years.
What special behavior does it exhibit?
A Walking Stick adapts to its surroundings by appearing to be a twig. It is only active at night (nocturnal). It has claws and suction pads on its feet to climb stems and branches.
Nymphs can regrow or regenerate a leg pulled off while escaping a predator. Each time it molts, the lost limb gradually grows back. After three or four molts the lost limb is completely grown back, a little shorter than the original. When an antenna is lost, the Stick Insect grows a new leg in its place. Adults no longer molt, so only nymphs can replace body parts this way.
Males of the Giant Spiny Stick Insect species are also called Thorny Devils. They have large, sharp spines on their hind legs. Their legs are used as fishhooks in Papua New Guinea.
Female Two-striped Walking Sticks are large and carry the smaller males around for long periods.
How does this bug affect people?
Walking Sticks do not seem to have a great impact on humans. There may be problems when they are brought to areas where they do not belong naturally. Common American Walking Sticks are sometimes thought of as pests because large numbers feeding at once can eat most of the leaves on a tree.
The Indian Walking Stick is native to Madagascar where captive colonies are often kept on hedges. The Indian Walking Stick is often used as a study animal by scientists.
Some people keep Walking Stick insects as pets.
The Two-striped Walking Stick is capable of squirting a strong-smelling defensive spray that is painfully irritating to the eyes and mucous membranes
McGavin, G. C. (2000). Dorling Kindersley handbooks insects spiders and other terrestrial arthropods. NY: Dorling Kindersley, Inc.
Miller, G. (1999). Nature’s children—stick insects. Danbury, CT: Grolier Educational.
||This Wikijunior article is a stub. You can help Wikijunior by expanding it.|