Feeding a Hummingbird That's Really a Moth

04-01-2001 // Stephen W. Kress

PLANTING PLENTY of nectar-producing flowers can lure hummingbirds into your yard. But while on the lookout for what John James Audubon called "glittering garments of the rainbow," you might spot a hovering hummingbird moth instead. In a classic example of convergent evolution, these swept-winged, stout-bodied moths dine on flower nectar and pollinate flowers in a way remarkably similar to hummingbirds. Like their avian namesakes, hummingbird moths can hover seemingly motionless, while tapping nectar reserves with their long, coiled tongue. Some species even have a green back, further adding to their hummingbird resemblance. But unlike the birds, these moths are late risers. They don't stir into action until the sun warms their wing muscles.

Hummingbird moths are members of the sphinx moth family. This enormously varied group gets its family name from the way the caterpillars can pull their front ends up into a sphinxlike pose when disturbed. While most sphinx moths visit flowers at night, hummingbird moths—also called clearwings because of the transparent patches on their wings—frequent gardens in full daylight.

Hummingbird moth caterpillars feed mainly on honeysuckle, hawthorn, snowberry and viburnum, but different species have different tastes. The caterpillars transform into pupae, which are enclosed in well-hidden, dense brown cocoons under fallen leaves. Some pupae spend winter there, transforming into flying adults the following spring. When more than one brood is produced—as happens in southern climates—a second set of adults will emerge in late summer or fall.

Since the moths' appearance varies by location, differentiating between the species is sometimes a struggle. Taxonomists generally agree that North America has four hummingbird moth species, which cover most of the country. Each species' wings have the characteristic transparent patches, and the males have a dramatic anal tuft.

Gardeners don't have to plant special flowers to attract the adults, but the larvae do require specific shrubs for food. If you're interested in enticing these pollinators into your yard, first find out which species range in your area, then grow some of the caterpillars' favorite plants. Following are some tips to attract and recognize the species.

  • Common clearwing (Hemaris thysbe): The largest and most common hummingbird moths, common clearwings range from Newfoundland to Florida, across to Texas, north along the eastern Great Plains, west to southern British Columbia, then north to southern Alaska. Look for narrow or broad bands on the abdomen and a muddy-yellow or brown thorax. Males have a distinctive black tuft at the tip of their abdomen. Plant hawthorn, honeysuckle, snowberry, cherry and plum trees or shrubs to feed their caterpillars.
     
  • Snowberry clearwing (Hemaris diffinis): Ranging from Nova Scotia to Florida, across to California and north to British Columbia, snowberry clearwings have more black markings on the thorax, abdomen and legs than other clearwings. Plant dogbane, snowberries and honeysuckle, especially dwarf bush, to feed their caterpillars.
     
  • California clearwing (Hemaris senta): Found in Colorado, New Mexico, Utah, Wyoming and west to California and north to British Columbia, California clearwings have brownish-olive or olive-green heads and thoraxes. The abdomen, which has a broad yellow band, is black or olive-green above and yellow below. Their wings have a very narrow brown border and the clear parts of the wings have a steel-blue luster. Little is known about the caterpillars of this moth.
     
  • Graceful clearwing (Hemaris gracilis): The least common of the four species, graceful clearwings range from Nova Scotia to central Florida along the East Coast and west through New England to Michigan. Look for a pair of red-brown bands on the sides of the thorax to distinguish them from common clearwings. The thorax varies from green to yellow-green and sometimes brown with white underneath. They have a pale red abdomen. Foods are probably similar to those eaten by other species, but little is known about the caterpillars of this moth.

Ornithologist Stephen W. Kress is the director of Project Puffin.

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