On our way to dinner one day, my daughter spotted what looked like a small hummingbird. We spent some time watching it and, at first glance, it looked like a typical hummingbird. It certainly flew like other hummingbirds I have seen, with the hovering motion moving from flower to flower. Then we noticed something strange. The little hummingbird had antennae! My theory was, it might somehow be a hummingbird mimicking an insect. After it flew off, we wondered what it was.
We looked up the smallest hummingbird in the world and found a picture of the bee hummingbird, which sounded like a plausible name for what we saw. But, from what we read, the bee hummingbird is typically about 5 cm long and is iridescent red, blue and green. What we saw was smaller than that and had very different colours — a brownish tinge on the wings with black and white stripes on the posterior.
With this in mind, we decided to look at it differently—maybe it was some kind of insect that looked like a hummingbird for some reason, instead of the other way around. That's when we discovered the Hummingbird Moth. We can't be certain that the insect we saw was a hummingbird moth since we don't have it to compare with our research, but we came up with some possibilities.
The one we saw may have been the Snowberry Clearwing (aka the Bumblebee Moth), Hemaris diffinis, because it had dark banding on its abdomen. But they do vary in their looks from place to place, so it might also have been the Hummingbird Clearwing Moth (aka the Common Clearwing), Hemaris thysbe (the name "Thysbe" might come from connecting the reddish brown body of the moth to the bloody veil of that character in the tale of Pyramus and Thisbe, which I had only known from the bit in A Midsummernight's Dream). In any case, the photo of the Common Clearwing did not seem to be anything like a typical moth, though some close up pictures show how furry its body looks. As its name suggests, it has clear wings, but the one we saw was moving too quickly to tell the opacity of the wings. And unlike what I expected of moths, the Common Clearwing flies around during the day.
But why would it look like a humming bird? The similarity to a hummingbird might be a form of mimicry, but I don't see any benefit to pretending to be a humming bird. Instead, this seems to be an example of convergent evolution, when organisms from very different body plans, like birds and insects, evolve into a similar result. Hummingbirds are a diverse group with many different species, so perhaps its feeding strategy is beneficial. They, however, tend to focus on specific kinds of flowers, usually red. Hummingbird moths are less picky although they do go for plants with longer flowers. They have remarkably long proboscises, which they can curl up under their head, but in the case of our moth, I only saw it extended and supposed that it was a beak. It was feeding on little trumpet-like purple flowers near the ground. The high speed flapping must use a lot of energy, but their mobility must be helpful in avoiding predators and finding food.
I am not the only one amazed by these creatures. They Might Be Giants even wrote a song about them. Have you ever seen a hummingbird moth? Were you as easily fooled as I was? Have you ever been late for dinner because of an intriguing scientific phenomenon? Leave your comments below.