Not a hummingbird – The hummingbird hawkmoth

Similar but unrelated

Due to their similarity to hummingbirds, hummingbird hawkmoth sightings are often falsely reported as hummingbird sightings. Their similarity can be accredited to a process called “convergent evolution”. Convergent evolution happens if two organisms without a common ancestor end up alike in looks and/or behavior because they have adapted to a similar ecological niche. Hummingbird hawkmoths and hummingbirds not only look alike, but both feed on nectar, using their long proboscis (a tubular mouthpart comparable to a tongue) and tongue, respectively, while hovering mid-air in front of the flower.

Built-in drinking tube

The hummingbird hawkmoth has the longest proboscis amongst diurnal (active during the day) flower-visiting insects in Europe. It is 2.5 – 2.8 cm long but rolls up when not in use. Although it sounds like a huge tongue for an insect, the tongue of another species of hawkmoth, the Wallace’s sphinx moth (Xanthopan praedicta) found in Madagascar, can be up to 28.5 cm long.

The hummingbird hawkmoth, and other moths of the moth family Sphingidae, play a critical role in the pollination of many plant species. Their long proboscis allows them to reach deep into the flowers to access nectar, unintentionally picking up pollen on their nectar coated proboscis, which they transfer to other flowers as they feed. The longer their proboscis the longer the nectar tube of the flower can be and thus a remarkable variety of hawkmoths and flowers with long nectar tubes have coevolved. 

Here's looking at you, kid

Like most other insects, hawkmoths have a compound eye, made up of countless tiny units arranged in a hemisphere. On the surface of the eye, these units are visible as polygonal shapes, the facets. When you look at a hawkmoth you may get the impression that its eyes are following you wherever you go. However, the moving dark spot you see is not a pupil. It’s a patch of facets absorbing most of the light coming from your direction. This is called a pseudopupil and can also be observed e. g. in the eyes of a mantis.

Unlike other hawkmoths, the hummingbird hawkmoth is active during the day and thus has developed some features not seen in other moths. The front area of the eye has bigger facets and more light receptors, which gives the moth a sharp, bright and very detailed image of the world in proximity. This special eye structure allows M. stellatarum to focus on a flower's entrance while hovering and feeding.

Accomplished navigators

Hummingbird hawkmoths are mainly distributed in Southern Europe but during the summer they cover great distances in a couple of weeks and migrate in great numbers to Central and Northern Europe. How individual insects manage to travel such long distances was recently studied in a species of the same family, the death’s head hawkmoth (Acherontia atropos). A research team in Germany investigated the impressive migratory ability of this nocturnal hawkmoth by fitting individual moths with transmitters and following them in a light aircraft to record their movements by GPS. The moths were able to maintain their flight trajectories over long distances thanks to their adeptness at leveraging favorable winds by flying slow at higher altitudes, as well as their ability to handle unfavorable conditions by flying faster and closer to the ground. The researchers concluded that an internal compass helps the moths maintain their trajectories independent of wind conditions. While the exact details of their migration patterns are still being studied, hawkmoths are a remarkable example of small insects capable of traveling long distances.