Blue-Butterfly Day was featured in Frost's collection, New Hampshire, published in 1923. It entered the public domain in the US January 1, 2019.
It is blue-butterfly day here in spring,
And with these sky-flakes down in flurry on flurry
There is more unmixed color on the wing
Than flowers will show for days unless they hurry.
But these are flowers that fly and all but sing:
And now from having ridden out desire
They lie closed over in the wind and cling
Where wheels have freshly sliced the April mire.