Clearwing moths a surprise for gardeners
Have you seen and puzzled over an “unidentified flying object" in your garden?
Perhaps this mystery creature looks like a hummingbird or a bee but just does not quite fit either identity. It’s likely that you have seen a clearwing moth.
Taxonomically, clearwing moths are Lepidoptera, the group containing butterflies and moths, and more specifically, are members of the sphinx moth family.
In western Pennsylvania there are two species: snowberry clearwing (Hemaris diffinis) and the hummingbird clearwing (H. thysbe). Both species are widespread in North America, although the hummingbird clearwing is more common in the eastern United States and the snowberry clearwing is more common in the western United States.
Clearwing moths have plump bodies with long front wings that resemble a ruby-throated hummingbird (Archilochus colubris). However, moth wings are covered in scales just like a butterfly’s wings. Both “clearwings” lose patches of scales on their wings, making the wings transparent except for scales on the edges and veins of the wings. Also defining their relation to butterflies and moths, a clearwing moth has a long, retractable proboscis for feeding on nectar.
Clearwing moths fly and move just like hummingbirds. The male can fan open bristles that resemble a “tail.” They are even able to hover in flight, and their wings make a detectable humming sound. Both characteristics add to the confusion of identifying one as a moth and not a hummingbird. One very discernible difference is size. A ruby-throated hummingbird is approximately three inches long and clearwing moths are smaller, averaging about one and a half to two inches.
Clearwing moths are found in a variety of habitats including forest edges, open meadows and fields and the backyard garden. Clearwings are active during the day. They feed on nectar from a wide variety of flowers including butterflyweed (Ascelpias tuberosa), purple coneflower (Echinacea purpurea) and Joe-pye weeds (Eutrochium spp.). Because they have a long proboscis, clearwing moths can access the nectar of long-necked flowers such as bee balm (Monarda didyma) and wild bergamot (M. fistulosa) that is not accessible to many other insects. In our garden, we find them most often on wild bergamot and now grow several large patches to keep them visiting.
Clearwing moths lay their eggs on host plants that their caterpillars will feed on until they pupate. Host plants include honeysuckles (Lonicera spp.), viburnums (Viburnum spp.), hemp dogbane (Apocynum cannabinum), snowberry (Symphoricarpos albus), hawthorns (Crataegus spp.), and cherries and plums (Prunus spp.). Caterpillars are plump and can be yellowish green or sometimes brownish. All have the spiked “horn” typical of most sphinx moth caterpillars. The caterpillars pupate and overwinter in a spun cocoon in leaf litter or on the ground, emerging in late spring or early summer when nectar sources become available.
To identify the clearwing moths visiting your garden, you need a little patience and must concentrate on key characteristics:
- The hummingbird clearwing moth is the most common. It has an olive-gold back, a reddish brown abdomen, and pale colored legs.
- The snowberry clearwing moth has a more black and yellow pattern, black legs and a black line running through the eye and down the side. Because of the black and yellow patterning, the snowberry clearwing may resemble a large bumblebee rather than a hummingbird to some.
If you think you see a hummingbird, or a large bumble bee in your garden, take another closer look; you might be treated to a visit by a clearwing moth. If you have questions about clearwing moths or perennials that attract them, call the Butler County Master Gardener Garden Hotline at 724-287 4761, ext. 7 or email the Master Gardeners at butlermg@psu.edu.
Mary Alice Koeneke is a Penn State Extension Master Gardener of Butler County.
