#phasmatodea

Phasmids are most known for their natural camouflage, making them difficult for predators to detect. But many species also have a secondary line of defense, in the form of startle displays (like flashing brightly patterned wings or making a loud noise), sharp spines, or poisonous secretions. Some species, such as the young nymphs of the Spiny Leaf Insect (Extatosoma tiaratum) have been observed to curl their abdomen upwards over their body and head to resemble ants or scorpions in an act of mimicry.

The defensive spray from one species, Megacrania nigrosulfurea, is used as a treatment for skin infections by a tribe in Papua New Guinea because of its antibacterial constituents.

On top of resembling sticks and foliage, a few species, such as the Common Stick Insect (Carausius morosus) are even able to change their pigmentation to match their surroundings.

Phasmids have an impressive visual system that allows them to perceive significant detail even in dim conditions, which suits their typically nocturnal lifestyle. They are born equipped with tiny compound eyes with a limited number of facets. As phasmids grow through successive molts, the number of facets in each eye is increased along with the number of photoreceptor cells. The larger size of the adult insects' eyes makes them more prone to radiation damage. This explains why fully grown individuals are mostly nocturnal. Young stick insects are diurnal feeders and move around freely during the daytime, expanding their foraging range.

Stick insects have two types of pads on their legs: sticky "toe pads" and non-stick "heel pads" a little further up their legs. The heel pads are covered in microscopic hairs which create strong friction at low pressure, enabling them to grip without having to be peeled energetically from the surface at each step. The sticky toe pads are used to provide additional grip when climbing but are not used on a level surface.

The informally named Phryganistria "chinensis" (as it has not yet been scientifically described) is the world’s largest stick insect, and the world’s longest insect overall, with the original record-holding female at 62.4 cm (2.05 ft) in total length (including extended legs) and 36.1 cm (1.18 ft) in body length. She was eventually surpassed by one of her captive-bred young, reaching 64 centimetres (2.1 ft) in total length.

Over 300 species of phasmid are known from the island of Borneo alone, making it the richest place in the world for Phasmatodea.

Stick insects, like praying mantises, show rocking behavior in which the insect makes rhythmic, repetitive, side-to-side movements (see gif above). The common interpretation of this behavior's function is it enhances crypsis (camouflage) by mimicking vegetation moving in the wind. These movements may also be important in allowing the insects to discriminate objects from the background by relative motion.

The eggs of some species such as the Common Walkingstick (Diapheromera femorata) have projections resembling elaiosomes (fleshy structures sometimes attached to seeds) that attract ants. When the egg has been carried to the colony, the adult ant feeds the elaiosome to an ant larva while the phasmid egg is left to develop in the recesses of the nest in a protected environment, safe from predators.

Many species of phasmids are parthenogenic, meaning the females lay eggs without needing to mate with males to produce offspring. Eggs from virgin mothers are entirely female and hatch into nymphs that are exact copies of their mothers.

Phasmatodea eggs resemble seeds or tiny baskets and have hard shells. They have a lid-like structure called an operculum at the anterior pole, from which the nymph emerges during hatching.