On our last morning in the cloud forests of Costa Rica, we saw what might have been a ghost:
This is a stick insect—to be precise, the species Trychopeplus laciniatus (Phasmatodea: Diapheromeridae). The order name Phasmatodea (sometimes Phasmida) is based on the Latin noun phasma ("apparition, ghost") or its etymon, ancient Greek ϕάσμα, a tribute to the exquisite camouflage that can make stick and leaf insects visible one moment and invisible the next. While most species in the order mimic twigs or foliage, T. laciniatus resembles the thick moss that clothes the trunks of trees everywhere in the cloud forests. Flightless, slow-moving, and undefended, it has evolved to stake its survival entirely on disguise.
It is hard to believe that all of the moss-like embellishments on the exterior of the insect are just chitinous cuticle.
Stick and leaf insects are herbivores with chewing mouthparts. Females lay eggs singly, rather than in batches, and let them fall to the forest floor instead of inserting them into plants or affixing them to a substrate. The order Phasmatodea is orthopteroid, meaning it is in the complex of insect groups, including cockroaches, mantids, and earwigs, that are all closely related to the grasshoppers and crickets (the Orthoptera).