What determines the size of butterflies?

Community and Forum → Insects biology and faunistics → What determines the size of butterflies?

Oleg Nikolsky, 11.06.2013 21:40

A question for specialists from an amateur.
On June 6, on the outskirts of Bryansk, I encountered an unusual phenomenon for me - there are a lot of butterflies, but they are all small in size, noticeably smaller than usual.

A large wet meadow, here and there with puddles in the ruts, overgrown with willow bushes, birches, black alders, oaks and various grasses - thickets of flowering buttercup, blue irises, ferns, veronica oak, umbrella and others.
Mother-of-pearl Brenthisinoare pushed around the bushes, from a distance they are very similar (including in miniature) to macaria brunneata moths near blueberry bushes. Sometimes there are Boloria selena, also smaller than the usual size. Draughtsmen generally look like some kind of black pigeon, slightly larger than the average thick-head. Even hawthorns, of which there are many again this year, are about a third smaller than their usual size. At the same time, pigeons and fatheads are the same size as usual. Of all the butterflies encountered, the largest were the Meadow Bear Diacrisia sannio and Cinxia Melitaea cinxia.

Now, actually, the question is: why exactly are small-sized butterflies in this place? It is unlikely that any weather factors of the previous season had an impact here - in other places near Bryansk this summer, with a large number of hawthorns, they are quite large, in flight they are difficult to distinguish from mnemosyne, which is also quite large in size. Maybe the reason is a lack of food for the caterpillars? Because of their large number, few people were able to eat their fill and grow up large? What does entomology say about this? Unfortunately, I didn't find anything clear and understandable on this topic.

My 2012 photo collection can be viewed on the website http://butterflies-32.net/.

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