Plant Cuttings

Moths go batty

By way of introducing some mirth* to the otherwise rather doom-and-gloom-laden previous news item (A heart(wood)-warming tale of methanogens), this zoo-centric tree-based story caught my eye. Andrei Sourakov (of the rather impressively named McGuire Center for Lepidoptera and Biodiversity – at the University of Florida’s Florida Museum of Natural History, USA) reports the curious case of ‘moth-massing’ in trees. However, unlike the extremophiles buried deep within solid poplar heartwood, these imaginative insects were found congregating in the hollow trunks of two individual trees, one Quercus falcata (Southern red oak), the other Liquidamber styraciflua (sweetgum).

Idia lubricalis
Image: Glossy Black Idia (Idia lubricalis) John B. / Wikipedia

Although it was not possible to identify the insects to species level, they are described as “litter moths similar to Glossy Black Idia (Idia lubricalis)”, and formed what appeared to be “monospecific diurnal roosts consisting of both males and females”. The reason for the aggregations – which involved up to 400 individuals on one occasion – is not known**, but this behaviour has been likened to the diurnal roosting of bats. Is this therefore evidence that moths evolved into bats? Or is that a mischievously misleading misunderstanding of evolution?*** Whatever it turns out to be, it’s certainly another interesting and intriguing insight into the hitherto unrecognised biology of trees. What natural curiosities await our discovery, we just have to learn to look beneath the surface.

* Those amongst you of a particular humorous disposition might recognise the wordplay that’s intended here since ‘mirth’ is how I hear the bizarre pronunciation of the word ‘moth’ effected by UK comedian Peter Sellers in his role as the Frenchman Inspector Clouseau in the Pink Panther film “A shot in the dark”…

** Lest those of a mothophobic nature fear that all hollow tree trunks harbour armies of moths, Andrei Sourakov does point out that this moss-aggregating behaviour (or MAB) was only observed in two trees … during the summer … in north central Florida (USA) … between 2010 and 2018 (i.e., he “found this phenomenon only twice among the many (likely over 30) hollow trees … examined over the years…”). But, it’s its apparent rarity that makes it something to treasure.

*** Ed. – most emphatically the latter, Mr Cuttings! Although it is noteworthy that here we have interesting examples of convergent evolution (“the process in which organisms that are not closely related independently evolve similar features”). However, the wings of moths and the corresponding ‘wings’ of bats serve the same function of flight through air, they are analogous structures (“similar structures that evolved independently in two living organisms to serve the same purpose”). Maybe we also here have evolutionary convergence in roosting behaviour.

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