Western Pygmy Blue Butterfly

When I was out looking at the Hoary Tansy Asters that have sprung up in the old play yard after the monsoon rains, I noticed an extremely tiny butterfly flitting around one of the lavender flowers fairly low to the ground. It circled the plant several times, alighting on the flower for a few seconds each time. I managed to get some photos.


It took me quite a while to find this butterfly in the butterfly guide, but I was able to identify it by the distinctive spots on the hindwing and the long body. It's a Western Pygmy Blue (Brephidium exilis). Believed to be the smallest butterfly in North America, it averages 15 to 19 mm. in length. I measured the flower across its full diameter - 25 mm., so you can get some idea of the scale of this little creature. There doesn't seem to be much blue on this particular butterfly, which may indicate that its a female.

[Several web sites state that the Western Pygmy Blue butterfly is the smallest in the world. However, on December 2005 its alleged status was supplanted by the discovery of the even smaller Sinai Baton Blue butterfly. The Sinai Baton Blue butterfly lives only on mountainside patches of wild thyme in an arid corner of the Sinai Peninsula in Egypt called Saint Katherine's Protectorate. This tiny butterfly has been the subject of studies of how vulnerable animals will go extinct in the face of rising temperatures.]