Hummingbirds and hawkmoths
One of the most remarkable cases of mistaken identity in the animal world in the British Isles involves a large but unassuming moth.
About the Hummingbird hawkmoth
Every year many people are taken aback as they see in their garden what appears at first sight to be a hummingbird hovering among the flowers. A careful check of the size and a closer look unmasks this imposter as a hummingbird hawkmoth, Macroglossum stellatarum.
The hummingbird hawkmoth is a day-flying moth with a wingspan of about two inches (50-58mm). It has a brown, white-spotted abdomen, brown forewings and orange hindwings. It is very swift on the wing and an expert hoverer. The wings beat so rapidly that they produce an audible hum and can be seen only as a haze. The darting movement from one flower to the next with the long proboscis uncoiled completes the illusion of a hummingbird. Another day-flying moth, the Silver Y, is often confused with the hummingbird hawkmoth, but is smaller and darker.
The hummingbird hawkmoth is abundant and resident all around Mediterranean countries, and across Central Asia to Japan. Its migratory habits are well documented, with many thousands regularly migrating northward in Europe in the spring. There is also evidence of a return migration in the autumn.
Hummingbird hawkmoths in the UK
In the British Isles they can be seen somewhere every year, and have been recorded in every county as far north as the Orkney and Shetland Islands. The numbers which reach our shores can vary greatly between years. The main season runs from June to September, with smaller numbers recorded throughout the rest of the year.
Hummingbird hawkmoth breeds regularly in the UK, and larvae have been found in most years in July and August. The favourite food plant is Galium (bedstraw) and Rubia (wild madder). The larva grows up to 60mm in length. It is very colourful with green or reddish brown body with white dots and dark, white and yellow stripes, black spiracles and a blue yellow-tipped horn.
The late summer peak in numbers is largely the result of emergence of locally raised moths. Even though the moths successfully breed in the UK, they are not able to survive the winter (in mild winters, small numbers may overwinter). Therefore, the continuing presence of this remarkable moth is dependent on the annual influx from southern France.
The hummingbird hawkmoth prefers to fly in bright sunlight, but it will also take to wing in dull weather, at dusk or dawn, and sometimes even at night. It is very strongly attracted to flowers that provide a plentiful supply of nectar, such as red valerian, honeysuckle, jasmine, Buddleia, lilac, Escallonia, petunia and phlox. It hovers in front of a flower, probes it repeatedly for nectar and then darts to the next flower. It has a remarkably good memory individuals return to the same flowerbeds every day at about the same time.
Why not a hummingbird?
Their native range covers most of the Americas. Hummingbirds are very difficult to keep in captivity, and so only a small number of zoos in the UK keep them.
Those that are kept, tend to be the larger, easier species. The smallest hummingbird in the world is the bee hummingbird of Cuba, and even this little jewel is significantly larger than the hummingbird hawk moth.
It has rarely been found even on the neighbouring islands, and so could never stray across the Atlantic. It has proved to be too difficult to keep in captivity.