Hawk Moths and Hummingbirds

Fooled again! While I was in my garden the other day, in the distance I saw a flash of wings and a tiny body bobbing in and out among the flowers. I was looking forward to seeing a Ruby-throated Hummingbird (Archilochus colubris). On closer inspection, I realized I had spotted instead a Hummingbird Clearwing Moth (Hemaris thysbe).

Hummingbird Clearwing Moth (Hemaris thysbe) feeding on Lantana. Hummingbird Clearwings can be distinguished from other hummingbird moths by the green and burgundy back. Notice the transparent wings which gives this moth its name. Photo by PopularOutcast / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

This member of the hawk moth family (Sphingidae) is one of four clearwing moth species in North America. Two are most common: the Hummingbird Clearwing and the Snowberry Clearwing (Hemaris diffinis). Although both are found throughout North America, the Hummingbird Clearwing is abundant in the east and the Snowberry Clearwing is more often seen in the west. Hummingbird Clearwings are easily identified by their fuzzy burgundy and green backs. The Snowberry Clearwing’s back is yellow and black. And you can tell the difference between these moths and the Ruby-throated Hummingbird by their size. At an inch-and-a-half (4–5.5 centimeters) long these clearwings are half as big as a hummingbird.

A Hummingbird Clearwing Moth getting nectar from Wild Bergamot (Monarda fistulosa), which is a Connecticut native plant. Notice the Syrphid Fly also on the flower. These flies are beneficial insects in the garden, eating pests as a larva. Photo by Judy Gallagher / CC BY (https://creativecommons.org/licenses/by/2.0)

July is a perfect time to catch a glimpse of this day-flying moth collecting nectar. If you have flowers with long corolla tubes—such as Meadow Phlox (Phlox paniculata), bee balms (Monarda spp.) like our native Wild Bergamot (Monarda fistulosa), and verbenas—there is a good chance you will see one feeding. These moths extend their long, straw-like proboscis in and out of flowers while beating their wings at more than 70 times per second—so fast they look almost motionless in the air!

Hummingbird Clearwing caterpillars (larvae) feed on the leaves of different Viburnums as well as other plants. Photo by snicolich

Here in Connecticut and farther north, the Hummingbird Clearwing’s life cycle has one generation. Females lay small green, circular eggs on the underside of the leaves of their host plants. These include viburnums, such as native Arrowwood (Viburnum dentatum), hawthornes (Crataegus spp.), honeysuckles (Lonicera spp.), snowberries (Symphoricarpus spp.), and cherries and plums (Prunus spp.). A week later, a green caterpillar with a spur on its hind end hatches to feed on these host plants. After about four weeks and several growth stages (called instars), the fully grown caterpillar burrows into the soil and metamorphoses into a hard-shelled, brown pupa that will overwinter in your garden.

Leaves are not litter and shouldn’t be raked to the curb but incorporated into your yard or garden. (c) Xerces Society.

So instead of raking your leaves and leaving them at the curb in the fall, consider using them as mulch under your trees and shrubs. You will not only be providing a place for these moths to overwinter, but feeding your trees and shrubs too.

Published by Jim Sirch

Jim Sirch is the author of Beyond Your Back Door, a weekly blog about nature in your neighborhood. He is also Education Coordinator for the Yale Peabody Museum, a UConn Master Gardener and board member of his local land trust. As a trained naturalist, he brings a deep understanding of geology, plants and wildlife and how they interact within a particular ecosystem. He holds a B.S in Forestry from West Virginia University, a B.S. from Miami University in Science Education; and an M.S. in Environmental Studies Administration from Antioch University. He is also the 2014 Sigmund Abeles Award recipient from the Connecticut Science Teachers and Supervisors Association for outstanding science teaching and professional development.

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