Fossil of world's oldest stick insect found in Liaoning prehistoric lode

Sometimes it is better not to be noticed.

A number of insect species look so much like sticks or leaves that they simply blend in with the foliage, providing camouflage that helps keep them out of the beaks of hungry birds hankering for a big bite of bug.

But this is no recent adaptation. An international team of scientists said they have discovered the fossil of an insect in China that lived about 126 million years ago whose appearance mimicked that of a nearby plant. It is the oldest-known stick or leaf insect that used such natural trickery, they said.

The insect, named Cretophasmomima melanogramma, was found in Liaoning province in northeastern China, part of the Jehol rock formation that has yielded many stunningly detailed fossils of creatures such as early birds and feathered dinosaurs.

The researchers realised the insect looked remarkably like the leaf of a plant that grew in the same place at the time that was a relative of the ginkgo tree.

The fossil showed wings with parallel dark lines that, when the bug was in the resting position, seemed to produce a tongue-like shape that could hide its abdomen, they said. The plant had similar tongue-shaped leaves marked with multiple lines.

The researchers think the insect evolved to look like these leaves - even their green colour - and concealed itself from predators by mingling with the foliage. Females of this insect were estimated to have been about 5.6cm long and the males a bit smaller.

The findings were published in the online journal PLOS ONE.