Clearwing Sphinx Moths (Updated)

Over the weekend we saw a couple of very cool day-flying moths that dart and hover much like hummingbirds. In fact, several years ago we got a phone call from a young neighbor asking if baby hummingbirds have antennae! These critters always create a bit of a stir among observers and I've seen several internet postings about them lately so I figure it is time for a blog post. The local TV weatherman even had a feature about them!

I wish I had shot some video but the still photos will have to do. Here is this moth coming in, proboscis unfurling, to get some nectar from this common milkweed in full bloom:

In a still picture it looks a lot like a bee, and in flight it acts like a tiny hummingbird. In fact, it is a clearwing sphinx moth, one of two species that occur here. This is probably the Snowberry Clearwing, judging by brown stripe on the sides of the thorax. The other is aptly named the Hummingbird Clearwing, and they are not all that easy to tell apart.

These moths are strictly day-flyers, and are not attracted to lights the way many moths are. Apparently the wings have scales to begin with, but lose them soon after the adult moth begins to fly, hence their transparent appearance. They are just a blur when in flight, and I've never seen one actually land on a flower. Here is another view:

Despite their furry, bumblebee-like appearance they will not sting or harm anyone in any way. They are valuable pollinators and a fun sight in any garden or meadow on a sunny day.

So watch for and enjoy these unusual moths. If you are fortunate enough to see one on milkweed, enjoy the scent and unusual form of the flowers too!

UPDATE:
July 11, 2013

Yesterday we were out and about and saw both the Hummingbird and the Snowberry Clearwings. Here is a shot of the Hummingbird Clearwing:

There are two features that pretty easily distinguish the two, although they are hard to see while the moth is buzzing around so fast! The front pair of legs of the Hummingbird Clearwing are white and those of the Snowberry Clearwing are black. (That feature does not show in the Peterson Field Guide to the Moths of Northeastern North America.) Also the Snowberry has a dark brown streak on the dorsal side of the thorax which is absent in the Hummingbird Clearwing. Here they are side by side for comparison: