walking stick or stick insect, names applied to extremely longbodied, slow-moving, herbivorous insects, forming a single family in the order Phasmatodea. Walking sticks have green, gray, or brown bodies that closely resemble twigs or grass stems. Most are wingless and have long antennae. They range from less than 1 in. to over 1 ft (2–33 cm) in length, thus including the longest insects in the world. The winged forms have two pairs of wings; the hind wings are often colored. Their excellent camouflage protects them from predators; in addition, walking sticks can emit a foul-smelling substance as a means of defense. Some tropical species bear sharp spines resembling thorns. Walking sticks, unlike most insects, have the ability to regenerate lost limbs. Their eggs, which look like seeds, are deposited randomly on the ground; these often pass two winters before hatching in the spring. The young resemble the adults but are smaller. Although principally tropical and Asian in distribution, walking sticks are also found in temperate regions of Europe and North America. One species, Megaphasma dentricus, is the longest insect in the United States, attaining a length of 7 in. (17.5 cm). Walking sticks are classified in the phylum Arthropoda, class Insecta, order Phasmatodea, family Phasmidae. See also leaf insect.