The Milbs Are Back

Most years mourning cloak butterflies signal spring’s arrival. This year it’s Milbert’s tortoiseshells.

The first one appeared a few days ago, while snow was still the predominant ground cover. The next day there were two. Warm temps and sunshine took a big whack out of the snow piles, just what the Milbs needed.

These ones were born last August and spent the winter sheltered beneath loose bark or in hollow logs. Their body fluids contain alcohols and glycerols — like antifreeze for your car — which keeps them from freezing when temperatures plummet and food isn’t available.

These winter-hardy butterflies lay their eggs on stinging nettles, the exclusive food of their caterpillars. We have a patch of nettles alongside one corner of our deck — I’ll watch for them there in the coming weeks.


Milbert’s tortoiseshell   Aglais milberti

17 thoughts on “The Milbs Are Back

    1. I’ve sort of tried to keep the nettles from spreading in the past but after realizing how important they are to the caterpillars I’ll leave them alone. Let me know if you find any caterpillars on yours, Eliza.

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  1. I’ve never heard of this butterfly, but it certainly is lovely. As for winter survival strategies, there are grasshoppers who do the same thing. I recently read of a researcher who’d frozen some grasshoppers prior to doing some testing. Lo and behold, one of them was quite alive after thawing out. Being a good sort, she took it outdoors, where it hopped away.

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    1. The colours are quite stunning, especially in early spring when most everything else around here is a drab brown. Easy to see why some call them fire-rim tortoiseshells.

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