Meet Your Neighbors

Sphinx Moths:
Bird and Bee Impersonators

Look! It’s a bee! It’s a hummingbird! It’s a sphinx moth!

Folks often mistake sphinx moths for a bird, a bee, or even a flying crayfish when they see their first one, according to Forest Preserve District of DuPage County naturalist Carl Strang. But Strang quickly reorients confused callers on these interesting insects.

Sphinx moths are so named because of their caterpillar — when alarmed, it will hoist its body to resemble that famous feline figure of ancient Egypt. This caterpillar, with a distinctive curved projection at its posterior, is also called a hornworm.

Like hummingbirds and bees, sphinx moths pollinate common as well as rare plants, including the federally threatened eastern prairie white fringed orchid. The moths, like hummingbirds, use their proboscis or long tongue to probe flowers for nectar. “They can even fly backward and forward like a hummingbird does,” says Strang. In Illinois, more than 40 species of sphinx moths, which belong to the Sphingidae family and range in length from about one to five inches, live in woodlands, prairies, and gardens.

Though most sphinx moths fly at night, several species feed during the day. One of these, the hummingbird clearwing moth, Hemaris thysbe, has a green, furry body and resembles a ruby-throated hummingbird. The larvae eat honeysuckle, viburnum, and hawthorn leaves; the adults sip nectar from butterfly bush, phlox, and lantana, among others. The smaller snowberry clearwing, Hemaris diffinis, looks like a bumblebee with its yellow body and black wings. Its larvae feed on honeysuckle and dogbane; the adults nectar on milkweed, thistle, and other plants.

While hummingbirds can’t smell very well, sphinx moths require a keen olfactory sense to sniff flowers and to sense pheromones, chemicals they release to attract mates. A week after the female lays eggs underneath leaves, the larvae hatch and begin eating nonstop for nearly a month. Then they become pupa and bury themselves into the soil. If disturbed, the pupa thrashes its abdomen to startle a predator and can even decapitate an ant. Depending on timing, pupae either overwinter in the soil or emerge as adult moths in summer.

Since most sphinx moths fly at night and often need to be identified in the hand, it’s difficult to gauge their population levels, says Morton Arboretum plant biologist Marlin Bowles. But it’s imperative that scientists learn what they can, he says, because plants such as the white fringed orchid depend on them for their survival.

Cathy Pollack, a U.S. Fish & Wildlife biologist based in Barrington, studied pollinators of this rare orchid all night long during the summers of 2005 and 2006 in Will and Grundy Counties. She captured the moths with special lighting and traps. To her delight, she found a state invertebrate of specialconcern, the hermit sphinx moth, Sphinx eremitus, whose larvae feed on bee balm, bugleweed, and other native plants, in the vicinity of the orchids. Pollack also observed orchid pollen on the adult moths’ tongues, confirming that they’d been nectaring on the rare plants.

Such finds are encouraging, says Pollack, since without sphinx moths, the white fringed orchid must be pollinated by humans. “We can’t possibly hand-pollinate all the orchids,” she says.

If you want to study sphinx moths in your yard, learn which native plants attract the species at both their larval and adult stages and plant them in your garden. During the day, “look for a clearwing moth hopping on different leaves,” suggests Strang. “They are tasting the leaves with their feet. When they find the right species, they’ll lay an egg by curling their abdomen underneath the leaf.”

And if you’re really adventurous, take a flashlight out at night to see if you can find one of the more secretive hummingbird impersonators having a midnight snack in your garden.

— Sheryl DeVore