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Stick insect advice: Make like a tree and leaf

ChinaScience

With their extraordinary ability to mimic twigs and leaves, stick insects are among nature's most renowned masters of disguise. 

But it's not just predators they've managed to avoid. Sneaky phasmatodae, or "ghost" insects, have also flummoxed scientists by leaving behind precious few fossil clues concerning their unique evolution.

But on Wednesday, researchers from China, France and Germany announced the discovery of a long-extinct species that lived around Inner Mongolia roughly 126 million years ago.

The insect, dubbed Cretophasmomima melanogramma, was described in  the journal PLOS One and would have existed during the time of the dinosaurs. Long and narrow, the bug probably used its wings as a leaf-like cloak to fool birds and rat-like mammals, according to researchers.

Lead study author Maomin Wang, a researcher at Capital Normal University in Beijing, wrote that the insect lived within the famous Cretaceous Jehol biota -- making it almost 77 million years older than what was previously believed to be the earliest stick insect.

Wang and colleagues uncovered three fossils of the insect -- one female and two male -- and wrote that their wings appeared to have dark, parallel lines. When folded back, the wings would have assumed a "tongue-like" shape that covered the insect's abdomen.

Researchers argue that the wings resembled a leaf-shaped plant organ called Membranifolia admirabilis. Although fossils of the plant organ have been found in the same region of northern China, it is unclear exactly what type of plant they belonged to.

The authors wrote that since today's stick insects mimic the same plants they eat, they believe this was probably the case in the Jehol biota. (To watch some videos about modern stick insects, click here.)

Researchers noted that the three specimens each measured roughly 2 inches long, with the female being slightly larger than the males. In modern species, the difference in length between males and females, or what's called sexual size dimorphism, is more pronounced.

"This new record suggests that leaf mimicry predated the appearance of twig and bark mimicry in Phasmatodeans," the authors wrote. "Additionally, it complements our growing knowledge of the early attempts of insects to mimic plant parts."

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