Eastern Tailed-blue Butterfly

Have you ever caught a fleeting twinkle of blue in a meadow or forest edge? You may have just witnessed a male eastern tailed-blue butterfly (Cupido comyntas) flit by on his way to a flower. The striking blue on the wings of the males can only be seen when the wings are open. The upper side of the wing on females is gray-brown, though the wings of both sexes are a dainty silvery-white with small gray and orange markings. Their namesake “tail” is barely noticeable, but a key identifying mark on the hindwings.

These butterflies are among the smallest in Pennsylvania and can be found in a variety of habitats, including urban gardens. Eastern tailed blues are known to gather around puddles and damp areas, a phenomenon in butterflies called puddling or affectionately nicknamed “puddle parties.” Many species do this to obtain nutrients like sodium and salts, which are not present in nectar but have important reproductive benefit, and to socialize, which helps in mate selection.

Photo by Bill Moses.