It's a little startling to discover that the thing you took for a twig on a tree actually moves around on six legs. Visual trickery occurs widely in the natural world, and sometimes even shows up in suburban gardens in the Chesapeake Bay watershed, in the form of a moth masquerading as a bird.
The clearwing hummingbird moth, Hemaris thysbe, belongs to the family Sphingidae, the Sphinx moths. Its rapidly beating translucent wings and habits of flying during the day and hovering to sip nectar from bright-colored flowers make it easy to mistake it for a tiny ruby-throated hummingbird; if it weren't for the antennae and extra legs, it would be easy to place this moth in a different order altogether.
Most Sphinx moths have stout bodies with strong, stiff, brightly patterned wings; as caterpillars they are similarly broad, hairless and usually display a hornlike projection near the rear of the body, which give them an aggressive appearance that they don't warrant. Sphinx moths' wingspans can range in size from 1-inch to 6-inches; most of these moths also lack tympana or organs for hearing. Adults transfer nectar from flowers through a long proboscis, which they coil beneath their head when not feeding.
The clearwing hummingbird moth is a small Sphinx moth species, but like others in this family, flies in daylight rather than at night. After hatching from pale green eggs laid on leaf surfaces, the various larval instars of Hemaris thysbe appear bright yellowish-green, with dark green bands and some reddish brown spots on the abdomen. The tail horn is yellow. Caterpillars consume the leaves of many varieties of plants but prefer those of the honeysuckle family and viburnum.
This species pupates in a thin cocoon, spun at the soil surface, sometimes protected by a thin layer of leaf litter. The pupa is dark brown and shiny. After it emerges from the cocoon, the moth's wings at first appear plum-colored to brownish black, but large areas of the wing's scales drop off after the first flight, leaving transparent, veined, window-like patches on each wing. Their bodies are spindle-shaped, usually an olive green, with red bands across the abdomen. Its green body 'fur' and these red bands-as well as its attitude as it feeds and the sound of its rapid wingbeats-closely resemble that of the ruby-throated hummingbird.
Clearwing hummingbird moths can be seen from May through September along the edges of forests, in meadows and in cultivated flower gardens from coast to coast in the northern United States, and in the south to the east of the Great Plains. They fly in urban, suburban and rural flower gardens throughout the Bay watershed, drinking the nectars of bee balm, thistle, red clover, phlox, snowberry, cranberry and lilac.