Three thousand species of stick insects and walking sticks can be found worldwide, mostly concentrated in tropical areas of South America, Southeast Asia, Australia, and Southeastern North America. They range from œ inch up to 12 inches in length, with either cylindrical stick-like bodies or flat, leaf-like forms. Many are wingless or have very small wings. Stick insects are nocturnal with mandibles used for chewing, long antennae and compound eyes. Females can reproduce without males and they scatter their eggs on the ground to make them look like seeds. They can secrete a foul-smelling liquid but their primary defense is camouflage. True to their name, stick insects and walking sticks look like twigs and will even sway to mimic the movements of the trees. They sometimes remove their legs to help them escape predators, knowing that their legs will regenerate. Most of these insects feed on the leaves of trees and shrubs, and there have been instances where they have damaged forests. In certain parts of the world these insects are kept as exotic pets.