Debris-carrying behaviour of bark lice immatures preserved in 100 million years old amber

Camouflage strategies, including several types of concealments, are known for several insect groups today, such as immatures of some species within reduviid bugs (Hemiptera), lace wings (Neuroptera), caddisflies (Trichoptera) and bark lice (Psocodea). However, camouflage has only rarely been reported in the fossil record. Here we report findings of four bark lice preserved in 100 Million year old amber from Myanmar, which represent the first fossil evidence for masking behaviour in Cretaceous representatives of Psocodea. All four of these, probably not conspecific, and immature bark lice carry sand granules and organic material atop their back, which probably resulted in camouflaging them against the background (e.g. bark) to avoid detection by predators. We briefly summarise concepts of camouflage and examples of decoration behaviour within insects, as well as possible receiver (i.e. predators) of the camouflage of the herein described bark lice. The exact phylogenetic position of the specimens remains unclear, due to the scarce fossil record of Cretaceous immatures of Psocodea, as well as extant immatures. This demonstrates the importance of findings as reported here, as a wide knowledge of morphology and development of a certain group is crucial to get an insight into their evolution and reconstructing environments in deep time.

Automated summary

The study reports on four bark lice fossils preserved in amber from the Cretaceous period, demonstrating camouflage behavior and providing valuable evidence for the evolution of Psocodea. These immature bark lice carry sand granules and organic material on their backs, potentially for camouflage purposes to avoid predators.