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Representative image

Moths rest en masse in hollow trees

ANI | Updated: Jul 29, 2018 14:27 IST

Washington D.C. [USA], July 29 (ANI): Generally known as loners, moths are now famous for their slumber parties in hollow trees.
Researchers at Florida Museum of Natural History spotted unusual pattern inside a giant southern red oak tree where more than 400 moths were found resting inside the hollow tree. The moths seemed to be resting en masse, waiting for night to arrive.
In their observation, the moths oriented themselves toward the top of the tree and away from the light. They roosted silently, each slightly apart from the others. They saw both male and female moths, but none were mating, and no larvae were feeding nearby or inside the tree, although the immature stages of the moth eat bark and other organic material.
"This is completely new. Nobody has recorded daily communal roosting behaviour in moths. This appears to be a unique behaviour in this species and an important part of its biology," said lead researcher Andrei Sourakov.
Only a few species of butterflies and moths are known to gather in groups, the most famous example being the millions of monarchs that converge in Mexico each winter. The zebra longwing butterfly and other species in the genus Heliconius roost in small clusters of about a dozen at night, and several species of butterflies and moths shelter as groups in cool spots to escape the summer heat.
The researchers captured what seems to be the first-known example of moths congregating daily, apparently to sleep, a roosting behaviour more commonly observed in bats, one of the moths' top predators.
Why the moths gather together is still unclear, but researchers think the behaviour could be a "safety in numbers" defence strategy. By late summer, several spiders had set up webs inside the hollow red oak, but a few predators are unlikely to make a dent in a population of hundreds of moths.
"Large numbers of prey in a confined space presents a challenging environment for predators. Spiders, for instance, would have to constantly repair their webs torn by these many moths. But most importantly, the percentage of lost prey is not significant enough to undermine the population. 'Safety in numbers' doesn't mean everyone is safe, but the population is safe," he added.
The moths use sex pheromones as a signal for assembling and plans to continue studying them to gain further insights into their life history and behaviour.
The findings published in the Journal of Tropical Lepidoptera Research. (ANI)