Phasmatodea

Common Name: Walkingsticks / Stick Insects / Leaf Insects / Phasmids

Greek Origins of Name: Phasmatodea, derived from the Greek “phasm” meaning phantom, refers to the cryptic appearance and behavior of these insects.

Spot ID Key Characters:

Prothorax shorter than mesothorax or metathorax
Slender body parts (twig-like)
Wings reduced or absent

Development:

Hemimetabola, i.e. incomplete metamorphosis (egg, nymph, adult)

Taxonomy:

Polyneoptera, closely related to Orthoptera and Dermaptera

Distribution:

Common in tropical and subtropical climates where they are found living on their host plants. Approximately 5 families and 32 species in North America and 7 families and >3600 species worldwide.

Life History and Ecology:

The leaf and stick insects are sometimes grouped as a family or suborder of Orthoptera. All species are herbivores. As the name “walkingstick” implies, most phasmids are slender, cylindrical, and cryptically colored to resemble the twigs and branches on which they live. Members of the family Timemidae (=Phyllidae) bear a strong resemblance to leaves: abdomens are broad and flat, legs have large lateral extensions, and coloration is primarily brown, green, or yellow. Most walkingsticks are slow-moving insects, a behavior pattern that is consistent with their cryptic lifestyle. In a few tropical species, the adults have well-developed wings, but most phasmids are brachypterous (reduced wings) or secondarily wingless. Stick insects are most abundant in the tropics where some species may be up to 30 cm (12 inches) in length. Females do not have a well-developed ovipositor so they cannot insert their eggs into host plant tissue like most other Orthoptera. Instead, the eggs are dropped singly onto the ground, sometimes from great heights.

Appearance of Immatures and Adults:

Antennae long, slender
Mouthparts mandibulate, prognathous
Body long, cylindrical
Prothorax shorter than meso- or metathorax
Leg segments long and slender
Tarsi 5-segmented
Wings often reduced or absent
Cerci short, unsegmented

Economic Importance:

In temperate zones, walkingsticks are seldom abundant enough to cause injury to their host plants. In the tropics, however, some species have been known to defoliate forest trees and cause economic losses to shrubbery and shade trees.

Major Families:

Phasmatidae (Walkingsticks) — mimic sticks and twigs
Timemidae (Leaf Insects) — mimic leaves and foliage

Fun Facts:

Phasmid eggs often resemble seeds. The eggs may remain dormant for over a year before hatching.
In some parts of the tropics, stick insects may be so abundant that eggs falling out of the trees may sound like rain on a tin roof.
Some walkingsticks are sold as pets. They are easy to rear if kept in a warm environment with fresh foliage from their host plant.
Glands located on the thorax of many species can produce a foul-smelling liquid that repels predators.
When attacked by a predator, the legs of some phasmids may separate from the body (autotomy). Some species can even regenerate lost legs at the next molt. These are the only insects able to regenerate body parts.
Several species produce offspring from unfertilized eggs (parthenogenesis). Males may be uncommon or unknown.
Some phasmids change color with changes in temperature, humidity, or light intensity. Pigment granules in the epidermis disperse at night or on cool days, darkening the cuticle and absorbing more heat

According to West Indian folklore, God often rides from place to place on a walkingstick. As a result, this cryptic insect has come to be known locally as a “God-Horse”. In 1990, the country of Barbados (the easternmost island in the West Indies) issued this stamp that illustrates a native stick insect, Bostra maxwelli.