Range:

All continents except Antarctica

Habitat:

Tropical forests and woodlands

Masters of disguise

Stick insects, as their name implies, are insects that have taken camouflage and imitation to the extreme by developing the appearance of a stick, leaf, or twig. Typically, these insects are shades of brown, although some may be green, black, gray, or blue. They live in tropical forests and woodlands throughout the world.

You might think that stick insects hide among sticks on the ground, hoping to blend in, but most stick insect species are usually found sitting right out in the open within the leaves of a tropical tree. They usually stay perfectly still, but when they need to move, they are even able to camouflage their motion. It is common to see them walk in a swaying motion, pretending to be a twig caught by the wind. Other stick insect species have lichen-like outgrowths on their bodies that help camouflage them on tree bark.


Other forms of protection

When camouflage is not enough, some stick insects use active forms of defense to handle predators. For example, the species Eurycantha calcarata can release an awful-smelling substance as a deterrent. Other species have brightly colored wings that are invisible when folded against their body; when they feel threatened, they flash open their wings, then immediately drop to the ground and again hide their wings. The predator is often confused as it searches for a brightly colored insect but sees only a pile of drab, brown sticks on the ground!

Other defenses are easier to spot, as with the Peruvian fire stick. This species releases a milky white substance that is an irritant to predators. As a result, they have the memorable red, black, and yellow colors of a distasteful—or disagreeable—insect.

The name of the stick and leaf insect order, Phasmida, is from the Greek word phasma, which means "a ghostly or unusual sight."
The American walkingstick and Peruvian fire stick can spray a defensive chemical that causes temporary blindness and intense pain in predators such as mice and birds.
Juvenile walkingsticks can drop off legs to escape a predator's grasp. They grow new legs at the next molt.
Most walkingsticks eat skin they have shed after a molt to recycle proteins and to keep their location a secret from predators.
The stick insect Pharnacia kirbyi wins the prize for the longest insect in the world. It can grow to 20 inches (50 centimeters) long.

Sometimes, the littlest things have the biggest impact. That’s the philosophy behind the Insect House in the San Diego Zoo’s Discovery Outpost. Opened in 2003, it has terrariums set into the walls to showcase stick insects as well as leafcutter ants, roaches, beetles, scorpions, spiders, and bees, giving you a rare opportunity to marvel at the planet’s spineless wonders.
Currently, our resident stick insects include jungle nymphs, leaf insects, Children’s stick insects, MacLeay’s spectres, New Guinea stick insects, and Lord Howe Island stick insects.

Temperature and humidity are monitored and adjusted to suit each individual species’ preferences. Full-spectrum lights illuminate each terrarium, providing the animals with the same range of light waves they would get naturally from the sun. Volunteers are on hand to answer questions and help you find what you’re looking for. Be sure to ask to see the stick insects!

All stick insects are vulnerable from human encroachment, pesticides, and habitat destruction. The Lord Howe Island stick insect Dryococelus australis is critically endangered. The San Diego Zoo is working closely with the Melbourne Zoo to establish a satellite colony. They are being reared off exhibit, and our participation is still in its early stages, but the Melbourne Zoo has been successfully rearing them for several years.