We all know that moths are common at night, but there are a few species of moths that fly during the day. One of these is the hummingbird clearwing moth (Hemaris thysbe).
The name is fitting: This large moth might be mistaken for a hummingbird because it hovers and beats its wings rapidly while unfurling its long tongue (proboscis) to sip nectar from pink and purple flowers, including beebalm (monarda), bluebells, phlox, honeysuckle and verbena. They can fly sideways and backwards, accelerate quickly, and these moths beat their wings about 60 to 70 times per second (!) when hovering — fast enough to produce a buzzing or humming sound that is within the range of human hearing.
It’s called a clearwing because parts of its wings are transparent. Its scientific name is also apt: Hemaris comes from the Greek word hemera, meaning “day,” which is appropriate for a moth that prefers sunlight. Thysbe comes from Ovid’s tale of Pyramus and Thisbe, a precursor to Romeo and Juliet, where two lovers end up taking their own lives. Thisbe’s blood-stained cloak is central to the climax, and in 1775, Danish zoologist Johan Christian Fabricius named the species thysbe because the moth’s reddish wing edges reminded him of that cloak.
Like other moths, a hummingbird clearwing emerges from its chrysalis with two-inch wings that are covered in colorful scales. However, during its first flight, many of the scales fall off, leaving transparent membranes, which look like small windows on the wings.
Why might moths have clear wings? Scientists think that clear wings help this moth hide from predators because transparency makes it more difficult to spot. Many water-based critters are transparent for this reason, but this characteristic is less common in land animals.
Female moths of this species emit a chemical scent (called a pheromone) from the tip of the abdomen. This scent attracts males. After the two mate, the female lays tiny, round, green eggs (but no ham) one at a time on the underside of viburnum leaves. Each egg hatches in about a week into a caterpillar with a spike, or horn, on one end. These little caterpillars are eating machines, eating from the underside of leaves, mostly at night, and hiding during the day. Scientists think that feeding at night reduces the risk of being eaten by birds. After about four weeks, when the caterpillar is done growing, it drops to the ground, spins a cocoon (chrysalis), and pupates hidden in leaves. Pupae spend the winter hidden among leaf litter; adult moths emerge in the spring—one more reason to leave scattered leaves alone until late spring: Clearwing moths may be overwintering in them.
Unlike most moths, hummingbird clearwings do not need to land on flowers to feed. Their ability to hover and extend their proboscis helps them move rapidly from flower to flower. Spending less time in one place, also helps them avoid predation. A bird looking for slow-flying moths to eat makes split-second decisions and may not immediately recognize a hovering clearwing as edible prey. This brief hesitation gives the moth time to escape.
Hummingbird moths are also important pollinators. Bees and other short- or medium-tongued insects cannot reach the nectar of long-necked flowers such as phlox like clearwings can , so moths are important pollinators of these plants.
At first glance, this insect might look like a hummingbird. A second glance reveals a moth. By the third glance, you realize that you’re seeing one of New England’s most remarkable pollinators—helping ensure that a wide range of crucial plants can reproduce and proliferate.
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