Yard Distraction

You can always find a distraction if you are looking for one.

~Tom Kite

The beautiful weather this week finds me outside starting some yard work – weed pulling, mulching, contemplating building some benches for the fire circle, etc. As is often the case, yesterday something caught my eye and pulled me away from my tasks for a few minutes. It was some rapid movement in a bed of Wild Blue Phlox (one of my favorite native spring wildflowers, Phlox divaricata). It was the blur of wing beats of a Hummingbird Clearwing moth zipping from flower to flower, gathering nectar with its long proboscis. Below is a photo I took a few years ago of one of the caterpillars. We have plenty of host plants for this species around the yard including some Viburnums and lots of Coral Honeysuckle.

– Hummingbird Clearwing Moth caterpillar (click photo to enlarge)

The spike at the tip of the abdomen helps identify this larva as one the Sphinx Moth group. Adult Sphinx Moths are all excellent flyers with many have swept back wings that resemble fighter jet profiles. We have two common species of day-flying Sphinx Moths in our area, the Hummingbird Clearwing (Hemaris thysbe) and the Snowberry Clearwing (Hemaris diffinis). In an earlier post, I detailed some of the life history of these beautiful day-flying moths.

The reddish colors on the wings and abdomen of the one that pulled me from my chores told me I was looking at a Hummingbird Clearwing, so named because they really do resemble tiny hummingbirds in both form and habits. This is an excellent example of convergent evolution where two two species develop similar features despite not sharing a common ancestor. Both the moth and the bird occupy similar ecological niches and have evolved similar characteristics to best take advantage of their lifestyle. Both have rapid wing beats that allow them to hover and move backwards. Both have physical traits that allow them to probe deep into flowers for nectar, and, surprisingly (to me anyway), both have evolved similar basic color patterns (though the moths are much more variable than the birds).

I spent a few minutes following the moth around the flower patch as it fed on the flowers of phlox (its primary focus), foamflower and one iris. Since I was supposedly working, my camera gear was safely tucked away inside, but I did have that other camera, my iPhone, in my pocket. So, I grabbed it and attempted (key word) to get some video if the buzzing insect.

Below are two clips, one showing the moth feeding at actual speed, the other at 25% of normal speed. In both, the wings are beating so fast that it is tough to get a clear view of them, but if you look closely at the slow motion video, you can see the shallow figure eight pattern of wing movement that helps with hovering like in a hummingbird’s wing beat. I have read conflicting reports on the speed of the moth’s wing beats, ranging from about 35 per second up to around 80+ per second. Either way, they are fast – so fast that you can actually hear a humming sound if you are close enough.

— Hummingbird Clearwing Moth feeding at Wild Blue Phlox

— That same footage at 25% actual speed

Note the long, curved proboscis (tongue) of the moth and how it so accurately inserts it into the center of each flower it visits. The moth uses its front two legs to help balance itself as it approaches each flower. You can also see how the proboscis, head, and legs are coated with pollen, indicating this busy insect is probably an efficient pollinator of many of our wildflowers.

After following the moth around for a bit, it zipped off across the yard and disappeared. I finally got back to my chores, but was happy to have yet another wild distraction come my way.

Tiny Hummers and Bumblebirds

Hummingbird Clearwing, Hemaris thysbe 1

Hummingbird Clearwing Moth

During my career at the NC Museum of Natural Sciences I once was forwarded a call from someone that was curious about something they had seen in their yard. She wanted to know what species of tiny hummingbirds were visiting her flowers. After a brief discussion, we came to the conclusion she was seeing one of a group of day-flying moths collectively known as Clearwing Moths, and based on her description of the colors, most likely the aptly named Hummingbird Clearwing.

Hummingbird Clearwing, Hemaris thysbe 2

Hummingbird Clearwing at Butterfly Bush

This common eastern species, Hemaris thysbe, has coloration and foraging behavior reminiscent of a Ruby-throated Hummingbird, but is much smaller. A Hummingbird Clearwing Moth has a wingspan of about 1.5 – 2 inches, whereas the bird, the Ruby-throated Hummingbird, has a wingspan of 4.5 inches. Yet it is easy to see how people could mistake these diminutive rapid fliers for the bird. They hover and flit from flower to flower sipping nectar with their long proboscis. Their wings have reddish borders and they often have a greenish hue to the “hairs” on their stout bodies. These photographs of the adult moths were taken last week while visiting my parent’s in southwest Virginia. They have several Butterfly Bushes (Buddleia sp.) which are magnets for these beautiful moths.

Hummingbird Clearwing, Hemaris thysbe 3

Hummingbird Clearwing wingbeat

One thing you notice when you watch one of these moths is the blur of their wings as they hover and feed. Try as I might, I could only occasionally get part of both wings in focus even at high shutter speeds. No wonder, as it is estimated they beat their wings 30-35 times per second (compare that to a Ruby-throated Hummingbird with an average of 50-60 beats per second). One thing the rapid burst of photos did reveal is the pattern of movement in the wings – the figure-8 motion (the photo above shows the start of the backward sweep of the figure 8), which provides lift in both directions.

Snowberry Clearwing, Hemaris diffinis 2

Snowberry Clearwing

I also noticed several individuals of the similar-looking Snowberry Clearwing (Hemaris diffinis) feeding on the Butterfly Bushes. They closely mimic bumblebees in coloration and are often called Bumblebee Moths. In one online discussion forum I even saw someone refer to these as looking half hummingbird, half bumblebee – a bumblebird! The main differences between them and the Hummingbird Clearwing is that this species tends to be slightly smaller and has a blackish abdomen with a yellow band (sometimes not complete) near the tip.

Snowberry Clearwing, Hemaris diffinis 1

Snowberry Clearwing on Butterfly Bush

Both species have a long proboscis they insert into flowers to obtain nectar. They often place their front pair of legs on the flower as they hover and feed.

Hummingbird Clearwing caterpilar

Hummingbird Clearwing caterpillar

Both Hummingbird and Snowberry Clearwings are members of the hawk moth or sphinx moth family, Sphingidae. They are among the few strictly diurnal (day-flying) members of that family and are found throughout most of the eastern United States and Canada. Their caterpillars are similar to many other sphinx moth larvae in that they have a distinctive curved horn on their posterior end (caterpillars of this family are often called hornworms). The Hummingbird Clearwing’s horn is often bluish and they have a row of orange and white spots along each side surrounding the breathing pores (spiracles).

Snowberry Clearwing caterpillar

Snowberry Clearwing caterpillar

Snowberry Clearwing larvae have blackened dots along their spiracles and a horn that is yellow at the base with a black tip. Both species use various species of Haw (Viburnum sp.) and Honeysuckle (Lonicera sp.) as host plants. I always look for them on Arrowwood Viburnum and Coral Honeysuckle in my area.

Snowberry Clearwing, Hemaris diffinis 3

Snowberry Clearwing cruising in toward a meal showing curled proboscis

If you have either of these host plants in your garden or woods, be on the lookout for the adults as they cruise and hover at your flowers in search of nectar. I see them at a wide variety of plants from non-natives like Butterfly Bush to native beauties such as Bee Balm and Phlox. Every time I see one I can’t help but pause and enjoy…and sometimes I even stalk them for an hour or more trying to get just the right photo, but I always want a better one…

Hummingbird Clearwing, Hemaris thysbe 5

Hummingbird Clearwing