Hummingbird moths are a group of insects in the Sphingidae family of moths. They are called hummingbird moths because of their ability to hover in front of flowers while drinking nectar, similar to hummingbirds. There are around 14 species of hummingbird moth found in the United Kingdom. Some of the most common species include the hummingbird hawk-moth, the convolvulus hawk-moth, the bedstraw hawk-moth, and the elephant hawk-moth.
Hummingbird moths are medium to large in size, with wingspans ranging from 2-4 inches. They have slender bodies and long proboscises which allow them to reach nectar at the base of long tubular flowers. Their wings beat at high frequencies, creating the humming noise that gives them their name. When not feeding, they often hover in midair, suspended by their rapid wing beats. This aerobatic flight behavior is unique among moths and sets the hummingbird moths apart.
In this article, we will look at the prevalence and distribution of the most common hummingbird moth species found in the UK. We will examine where they are most abundant, their flight seasons, habitat preferences, and any population trends that have been observed. Understanding the ecology and natural history of these fascinating insects can help us appreciate the biodiversity around us and make more informed conservation decisions.
Distribution and Habitat Preferences
Hummingbird moths are found throughout much of Britain, but they tend to be more common in southern England. The warmer climates in the south allow for multiple broods per year, boosting overall population numbers. Northern England, Wales and Scotland host more modest populations that are limited to producing just one generation per year.
Within England, key hotspots for hummingbird moth diversity include the chalk grasslands of the North and South Downs, gardens in London and the Home Counties, brownfield sites in urban areas, and nature reserves and wildflower meadows across the south. Heathlands, coastal habitats, woodland edges, and areas with abundant nectar sources also provide good habitat.
Different hummingbird moth species have slightly different habitat needs:
Hummingbird Hawk-Moth
The most widespread species across England and Wales. Found in a variety of flowery, open habitats including gardens, parks, woodland clearings, heathlands and scrub. Particularly fond of habitats rich in nectar plants like buddleia, petunias, honeysuckle, and red valerian.
Convolvulus Hawk-Moth
Mainly restricted to the south-east of England. Favors dry, open habitats including chalk downland, coastal cliffs, quarries, railway cuttings, and brownfield sites. Larval food plant is bindweed, so found where this grows.
Bedstraw Hawk-Moth
Centred around the Chilterns but spreading across southern England. Found in chalk downland, limestone grassland, scrub, woodland edges, hedgerows, quarries and railway embankments. Caterpillars feed on bedstraws.
Elephant Hawk-Moth
Widespread across England and Wales.occupies woodland, hedgerows, gardens, parks, and meadows. Caterpillars feed on willowherbs, fuschias and other common plants.
Flight Season
Most hummingbird moth species are active between May and September, with peak numbers seen between June and August. However, a few species extend their flight season into the autumn months:
Hummingbird Hawk-Moth:
May to October, with peak numbers in August.
Convolvulus Hawk-Moth:
May to September, peaking in July/August.
Bedstraw Hawk-Moth:
June to October, with a peak in August.
Elephant Hawk-Moth:
May to August, peaking in June/July.
Some species like the hummingbird hawk-moth and bedstraw hawk-moth occasionally remain active into November or even December if the weather stays mild. The number of broods per year also impacts flight season duration. Species like the elephant hawk-moth with just one generation will have a shorter flight period compared to those like the hummingbird hawk-moth which can produce two or three generations from May to October.
Population Trends
According to data from the Rothamsted Insect Survey, many hummingbird moth species have declined in the UK over the past 50 years. However, some appear to be faring better in recent decades:
Hummingbird Hawk-Moth:
Steady increase since the 1970s, possibly aided by climate change allowing more generations per year.
Convolvulus Hawk-Moth:
Declined until the 1990s but has since made a partial recovery. Still scarce across much of its former range.
Bedstraw Hawk-Moth:
Underwent steep declines but is now recovering well in southeast England. Remains rare in Wales.
Elephant Hawk-Moth:
Widespread and holding steady, with some evidence of increasing range expansion northwards.
The reasons for declines are not fully clear but likely involve habitat loss, insecticide use reducing larval survival, and climate change impacts. More flower-rich habitat creation, chemical-free gardening, and limiting the impacts of climate change will likely aid hummingbird moth conservation.
Relative Abundance and Total Populations
It is difficult to estimate absolute population sizes of hummingbird moths across the UK. They can be numerous in suitable habitat but fluctuate widely between years. However, relative abundance monitoring at sites over time can reveal population trends.
Rothamsted data suggests the hummingbird hawk-moth is probably the most abundant species, albeit patchily distributed where habitat is favorable. Convolvulus and bedstraw hawk-moths are much more locally distributed and Scarce. Elephant hawk-moths occupy an intermediate level of abundance – common and widespread but not occurring in the densities of hummingbird hawk-moths.
Very approximately, hummingbird hawk-moth numbers likely reach into the tens of thousands, elephant hawk-moths into the hundreds of thousands, and convolvulus/bedstraw hawk-moths in the thousands annually. However, further research would be needed to constrain these estimates.
| Species | Relative Abundance | Population Estimate |
| Hummingbird Hawk-Moth | Abundant | Tens of thousands |
| Convolvulus Hawk-Moth | Scarce | Thousands |
| Bedstraw Hawk-Moth | Scarce | Thousands |
| Elephant Hawk-Moth | Common | Hundreds of thousands |
Conclusions
In conclusion, several species of hummingbird moth are found across Britain, with hotspots in southern England. The hummingbird hawk-moth is the most abundant and widespread, occupying a variety of flowery habitats. Convolvulus and bedstraw hawk-moths have more restricted distributions centered on southeast England. Elephant hawk-moths are common across England and Wales.
Flight seasons peak in midsummer but some species remain active into autumn. Populations of most species declined historically but some are recovering well in recent decades. Creating more wildlife-friendly habitat will help provide nectar sources and aid hummingbird moth conservation. Their fascinating hover-feeding behavior and long-distance migrations make them an important component of the country’s biodiversity.
