Hummingbird and Snowberry Clearwing Moths
By Kim Smith
Startled! is an apt description of the reaction most gardeners experience when first they encounter a clearwing moth. Hovering while nectaring, with wings whirring rapidly and audibly, is it a miniature hummingbird, enormous furry bee, flying lobster, or mutant new world creature?Hummingbird Clearwing Moth (Hemaris thysbe) nectaring at Verbena bonariensis
The family Sphingidae are easily identified in both their adult and caterpillar forms. The medium-to-large-sized sphinx, or hawk, moths have characteristic robust, chunky bodies tapering to a point, and slender wings, which are adapted for rapid and sustained flight. Often mistaken for hummingbirds, the Hummingbird Clearwing Moth (Hemaris thysbe), with green tufted body and ruby colored scales, suggesting the male hummingbird, and the Snowberry Clearwing Moth (Hemaris diffinis), with the gold and black striped color pattern similar to that of a fat bumble bee, mimic both the bees and birds they fly with during the day. The ability of certain Sphingids to hover in mid air while nectaring is unusual in nectar feeders and has evolved in only three species: Sphingids, bats, and hummingbirds. Sphinx moths also do an exceptionally unusual movement called “swing-hovering,” swinging from side to side while hovering, it is thought, in an effort to escape predators lying in wait amongst the flora.
Sphinx moths are grouped together because their caterpillars hold their head and thorax erect in a sphinx-like fashion. Most larvae have a horn protruding from their last segment. For this reason, they are often called hornworms. The adult sphinx moth is a powerful flier and usually has a long proboscis suitable for tubular-shaped flowers with a deep calyx, such as trumpet vine. The slender wings must beat rapidly to support their heavy bodies. The names of many sphinx or hawk moth species correlate to their caterpillar host plant, to name but a few examples: Catalpa Sphinx, Huckleberry Sphinx, Paw Paw Sphinx, Cherry Sphinx, and Elm Sphinx.
The order Lepidoptera is comprised of butterflies, moths and skippers. The name is derived from the Greek lepidos for scales and ptera for wings. Their scaled wings distinguish them as a group from all other insects. Shortly after the Hummingbird and Snowberry Clearwings are born, they immediately begin to shed their wing scales, hence the common name clearwing moth. While nectaring, moths receive a dusting of pollen as they brush against the pollen-bearing anthers. Their fuzzy, fur-like scale-covered bodies are an excellent transporter of pollen. Because moths are on the wing primarily at night, moth-pollinated flowers are often white and pale, pastel-hued and tend to be sweetly scented. White flowers are more easily distinguished in the evening light, whereas colorful flowers disappear. Adult clearwing moths are diurnal (day flying) and nectar at a variety of flowers. In our garden, they are most often spotted at our native Phlox ‘David,’ bee balm (Monarda didyma), purple-top Verbena bonariensis, and butterfly bushes with blue and white flowers. The larvae of Hummingbird Clearwings feed primarily on viburnum, honeysuckle, and snowberry (all Caprifoliaceae), and less commonly on hawthorn, cherry, and plum (Rosaceae). Snowberry larvae feed on honeysuckle and snowberry.
For the most part, Sphinx moths are on the wing at night, although the beautiful White-lined Sphinx (Hyles lineata) is often seen at dusk. The forward wings are dark olive brown streaked with white. The hind wings are black with a vivid band of rose-pink. Found throughout North America, both larvae and adults are consummate generalists. The caterpillars feed on the foliage of apple trees, four-o’clocks, evening primrose, elm, grape, and tomato. The adults nectar at a wide variety of flowers including larkspur, gaura, columbine, petunia, moonflower, lilac, bouncing bet, clover, Jimson weed, and thistle. White-lined Sphinxes are drawn to lights and those that remain in the garden the next morning are quite subdued, and may come to your finger.
Orchids often have a symbiotic relation to very specific sphinx moths. The starry white, six-petalled Comet Orchid (the French common name, “Etoile de Madagascar” means “Star of Madagascar”) produces nectar at the bottom of an extremely long corolla, nearly a foot in length. Star of Madagascar (Angraecum sesquipedale) was predicted by Charles Darwin to have a highly specialized moth pollinator with a proboscis at least that long. “Angraecum sesquipedale has nectaries eleven and a half inches long, with only the lower half filled with very sweet nectar…it is, however, surprising, that any insect should be able to reach the nectar: our English sphinxes have probosces as long as their bodies; but in Madagascar there must be moths with probosces capable of extension to a length of between ten and twelve inches!” (Darwin). The giant hawk moth Xanthopan morganii praedicta (“the predicted one”) was named appropriately upon its discovery, after Darwin’s death.
Etoile de Madagascar and Hawk Moth Xanthopan morganii praedicta
Image courtesy wiki commons media
Co-evolution, the specialized biological embrace of two species, bears both benefits and risks. Each partner benefits in that no energy is wasted on finding ways to reproduce. The risk lies in becoming too dependent on a single species. If one half of the co-evolved partnership perishes, the other will surely become extinct as well.
This article was first published on August 3, 2011 and was subsequently republished by the New England Wildflower Society.