Photo: Myrmeleontoid larvae from mid-Cretaceous Burmese amber. Credit: Wang et al. Sci. Adv. 2016; 2 : e1501918

Dinosaur Era insects went to great lengths to disguise themselves, reveals a rare assemblage of camouflaged bugs frozen in amber.

The insect fossils, which date to 100 million years ago, provide the oldest direct evidence of camouflage behavior utilizing debris, according to a study on the finds that is published in the journal Science Advances.

Myrmeleontoid larvae from Mid-Cretaceous Burmese and French ambers. Credit: Wang et al. Sci. Adv. 2016; 2 : e1501918

"Some animals actively seek to hide by decorating themselves with materials, such as sand, vegetal debris or arthropod remains (like insect and crustacean bits) from their environment, to conceal the features of their bodies and to match their backgrounds," wrote lead author Bo Wang and colleagues, describing the camouflage behavior.

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In this case, the creatures in disguise were green lacewing larvae, split-footed lacewings, owlflies and assassin bugs. All were found fossilized in Burmese, French and Lebanese ambers that the researchers analyzed.

Photo: Green lacewing larvae from mid-Cretaceous Burmese amber. Credit: Wang et al. Sci. Adv. 2016; 2 : e1501918

Wang, from the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences, and his colleagues discovered the insects used a variety of debris to cover themselves. The materials included remains of other insects, grains of sand, soil dust, bits of leaves, wood fibers and other plant matter.

Animals that might have lived alongside these insects in disguise could have included everything from dinosaurs to the world's earliest bees.

While the camouflage obviously did not save the insects from their amber entombment, it does show that they were pretty smart, the scientists suggest.


Image: Reconstruction of green lacewing larva based on the fossil finds. Credit: Wang et al. Sci. Adv. 2016; 2 : e1501918

Wang and his team explained that "debris-carrying, a behavior of actively harvesting and carrying exogenous materials, is among the most fascinating and complex behaviors" because it requires "an ability to recognize, collect and carry materials," along with other skills and evolved adaptations.

The scientists demonstrated their own cleverness by performing detective work that sheds light on what might have happened just before the insects died.

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Most of the Burmese amber lacewing larvae were preserved with hair-like tiny growths produced by particular ferns known as gleicheniacean ferns. Two green lacewing larvae were preserved carrying these plant objects, suggesting that the larvae were closely associated with the ferns' habitats.

Photo: A gleicheniacean fern (Polypodium californicum). Credit: Manfred Werner, Wikimedia Commons

Since gleicheniacean ferns tend to colonize areas right after fires, the researchers deduced that the amber-associated trees released their resin during or just after fires.

"This supports a relationship between fire events and the high production of plant resins," according to Wang and his team.

The fiery look of amber may then tell us something about how it was produced, such as what likely happened when droplets of tree resin first froze the 100-million-year-old camouflaged insects in their tracks.

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