Oldest evidence of insects swarming has been discovered in a Jurassic-era fossil

By Gwyn Wright via SWNS

The oldest evidence for insects swarming has been discovered in a Jurassic-era fossil of hundreds of mayflies.

The fascinating fossil contains the body, appendages and wings of 381 mayflies from the period that spanned 201 to 145 million years ago.

Although older insects have been found, some preserved in amber, this is the first evidence that they swarmed like clouds of mosquitoes still do today.

The fossils were found by a doctoral student in the Xiwan Basin of Hezhou City and it is the first discovery of this mayfly family in China.

The researchers have decided to call the area where the fossils were found the Xiwan Biota.

Other insects, plants and even shark egg capsules were also discovered there.

Mayflies spend most of their life in the aquatic environment as nymphs, and adults tend to live from as little as one or two hours to a few days.

During their short adult phase, male mayflies form dense swarms and females must find mating partners as they fly in and through them, where they copulate and ultimately locate a suitable place to deposit eggs.

This behavior was previously only known in crown mayflies but the findings suggest it was already well-established in these mayfly ancestors at the beginning of the Jurassic era.

Some Jurassic mayflies emerged all at once in large swarms, representing a "pulse" of insects moving from the water to land.

This pulse probably led to massive ecosystem fluxes in waterside habitats with impacts on basic ecology.

Zhang Qianqi from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences, who found the fossils, said: “Aquatic insects play an important role in aquatic food webs, acting as consumers of aquatic plants and animals.

“In return, they are consumed by fish and other predators.

“But aquatic insects can also be important parts of food webs on land when they emerge as adults from the water and fly to disperse and find mates.

“In addition to providing food bonanzas for predators, emerging insects can also have a fertilizing effect on plant communities next to lakes and streams when they die and decompose.

"Our finding highlights the underappreciated ecological significance of insects in short-lived feeding bonanzas and mass mortalities in deep-time lacustrine ecosystems.”

The findings were published in the journal Geology.