When I tell someone that I am interested in moths, such as the Elephant hawk moth, I usually see a puzzled expression on their face, followed by an enthusiastic ‘oh’ and an awkward silence…that’s generally my cue to jump in and try to convert them to thinking beyond clothes that look like Swiss cheese!
So what are moths?
Moths (including elephant hawk moths) are closely related to butterflies in the insect order Lepidoptera, and there are over 2,500 moth species in the UK alone, compared to only 59 butterfly species. As a general guide moths have several differences to butterflies, including superposition eyes designed for low light conditions (butterflies have apposition eyes), feathered antennae (rather than club shaped), unfolded wings when at rest (butterflies rest with their wings closed upright) and the presence of a frenulum (connects hind and fore wings for more efficient flight). However, not all of these differences are exclusive, and their presence does vary depending on species.
Are moths declining?
Although there are some day-flying moth species, most are night-flying, and sadly ‘out of sight, out of mind’ is all too true for these insects. However, over recent years there has been a growing appreciation of their importance to the health of the natural environment, particularly as pollinators. This increasing awareness has been partly driven by the realization that moth populations are declining in the UK, as well as other countries. In the UK the overall number of moths have declined by 28% since 1968 with over 60 becoming extinct in the 20th century. The likely knock-on effect of this decline is already being felt with a decrease in the abundance of bats over farmland and a drop in our Cuckoo population. However, the good news is, that despite all of this there are still lots of opportunities to see some amazing moths using a variety of techniques including sweep netting, sugaring, wine ropes and the use of light traps. Light traps are set at night using bulbs that emit light in the UV range to attract moths, which once captured, are counted and identified, and then released to continue their nights activities.
The Elephant hawk moth
One of the most impressive moths you are likely to encounter on a moth trapping night is the elephant hawk moth (Deilephila Elpenor), a member of the family Sphingidae. This is a large pink moth shaped like a Vulcan bomber that is commonly found across the UK. Its name comes from the fact that its caterpillar looks like an elephant’s trunk. It can be confused with the small elephant hawk moth, which is also pink coloured, but as the name suggests is smaller, and lacks a pink stripe down its abdomen.
The elephant hawk moth has a wingspan up to 6 cm and both male and females are a similar body size. Females may be slightly less brightly coloured. It lives in a wide variety of different habitats including urban gardens, hedgerows, woodland, grassland, heathland, and sand dunes. The adult moth can be observed between the months of May to early August (and sometimes September) when it is active from dusk to dawn. Once the sun comes up it takes shelter on one of its host plants and awaits the evening.
Elephant hawk moths feed on the nectar of night-scented flowers such as honeysuckle. Their method of feeding is not to land on the plant as other insects usually do, but to hover in front of it and extract the nectar using a long tongue (proboscis), similar to a hummingbird. This feeding activity expends a large amount of energy and to avoid flower misidentification (which would be an energy-costly mistake) the moth has evolved the ability to identify different wavelengths in low light conditions, effectively identifying host plants by colour, as well as possibly using the flowers fragrance.
The adult moth can live up to 5 weeks assuming it reaches old age. However, a variety of creatures feed on moths including birds, bats and other insects such as spiders, which share their habitat and can lure them in using brightly coloured marks on their body which mimic the colours of their host plants.
Elephant hawk moth caterpillar – or a snake in the grass?
Mating takes place during the night when the females release pheromones that can be detected by males over long distances. They then lay single or pairs of eggs on suitable host plants such as fuchsias, alfalfa, and lavender and the caterpillars (larvae) hatch after 10 days (late June to September). Once hatched, they munch their way through these plants at an impressive rate, eventually reaching around 3 inches in size. The final instars (last caterpillar stage) vary in colour from dark brown to green and although it’s not clear why there is such variation it may serve as a defensive mechanism, where birds which are searching for one colour may overlook the other. Caterpillars also have a single horn on the end of the body and a pair of large black eyespots.
When threatened, the caterpillar will rear up and swell the eyespot end of its body, making it appear head-like. This is thought to mimic the head and eyes of a snake, and will look quite threatening, particularly when the caterpillar is partially hidden in foliage. Any hungry bird will be forced to react quickly to this potential threat, and will likely beat a hasty retreat, rather than risk becoming a meal themselves.
After approximately a month (late summer, early autumn) the caterpillars bury themselves below the soil surface or beneath some leaf litter and surround themselves with a rather flimsy silk cocoon to pupate as a chrysalis (pupa). Here they will overwinter and emerge as adults the following year to begin the cycle all over again.
So why are elephant hawk moths pink?
Many night flying moths have bright colours and are also richly patterned. This often reflects their environment and the host plants that they feed on, allowing them to blend into the background and avoid predation. Adult elephant hawk moths feed on several brightly coloured pink flowering plants and this is likely the reason they have evolved their distinctive colouration. Some moths can also incorporate chemical compounds from the plants they feed on, and these are sometimes then used as toxins to deter predators.
Bibliography
Field Guide to the Moths of Great Britain and Ireland: Third Edition (Bloomsbury Wildlife Guides) 15 Oct. 2018. Paul Waring, Martin Townsend, Richard Lewington.
Moths in decline. Butterfly Conservation, 2023.
Moth recording techniques. Atropos, 2023