THE occurrence of household moths in Britain has seen a striking rise in recent years according to English Heritage. The anger and hatred of those who’ve survived a moth infestation is understandable, but most moths are unfairly maligned.

Unlike butterflies, which form a group of all the descendants of a single ancestor, moths are much more genetically diverse, having diverged from each other at an earlier point. There were early moths 300 million years ago, which adapted into modern moths alongside early flowers.

There are 160,000 known species of lepidoptera (moths and butterflies) worldwide, and more are still being discovered. While there are just 59 species of butterfly found in Britain, there are 2,500 known moth species, 900 of them “macro” moth species with wingspans generally longer than 2cm. Surprisingly only three moth species (all micro-moths) live indoors and cause damage to clothing and carpets.

Moths’ incredible diversity makes them hard to define. The single true distinction between moths and butterflies is the shape of their sensory antennae, which in butterflies are club-shaped, but in moths take a huge diversity of forms. Other than that, most moths share several characteristics, although there are exceptions to each.

Moths tend to be nocturnal, and therefore dull-coloured, with large sensitive eyes. They also generally look “fluffy” because their scales are larger than butterflies. They tend to rest with their wings flat and open rather than closed together.

Although some moths drink nectar, many adult moth species don’t eat at all. Clothes moths don’t have functioning mouths and live as adults for between two to four weeks just off the energy stored by the larvae that eat your clothes.

Moth larvae munch through the keratin that makes up natural fibres like silk and wool that make up their preferred homes. The adult moth life-cycle is taken up with mating and laying the eggs that will hatch to form the next generation of grubs.

Although in the wild, these moths can also eat the fur and feathers of dead animals, domestic moths are part of the history of clothes, as well as books, where they can be found eating through decaying paper and book bindings as well. The Exeter Book, a book of Anglo-Saxon riddles written over a thousand years ago in a 10th-century monastery, includes an unmysterious riddle about a moth grub:

A moth ate words. I thought that was a marvellous fate,

that the worm, a thief in the dark, should eat

a man’s words — a brilliant statement

and its foundation is strong. Not a whit the wiser

was he for having fattened himself on those words

To fight the tide of moth destruction, people throughout history have invented preventative measures, including pesticides like naphthalene moth balls, which are now banned in the EU for their extreme toxicity, both to the environment and when accidentally eaten by pets and children.

At the Natural History Museum in London, when moths threatened to destroy the fur and feathers of precious specimens, a different strategy was adopted to reduce the moth population. Male moths were coated in female moth pheromone, reducing the moth population by 50 per cent as male moths found each other instead of a viable mate.

The caterpillars of other species of moths threaten crops. One such species, the diamondback moth, poses a serious threat to crops of cauliflower, broccoli and cabbage. Just like the development of antibiotic resistance in bacteria, the overuse of strong pesticides has produced synthetic pesticide resistance in these moths.

Caterpillars that develop random mutations in their DNA conferring resistance to pesticides are less likely to die, and are therefore more likely to pass on their genes. This year in January, the first genetically modified diamondback moths were released in an attempt to combat the pest. The genetically modified male moths contain a “limiting gene” which prevents their offspring from reproducing.

These moths thereby significantly reduce the numbers of caterpillars hatching in the subsequent generation, without the use of poisonous chemicals. The genetic modification is also self-limiting, as the offspring that carry it are not viable, reducing the likelihood that the genes will be passed further out into the environment beyond the farm where they are released.

Although this was the first example of genetic modification for control of moth populations, the same strategy has already been used successfully to reduce mosquito populations where the risk of deadly diseases passed to humans by mosquito bites is severe.

But moths are a lot more than just unwanted pests. It is another type of moth grub, Bombyx mori, or silk-worm that is farmed to produce silk itself from its cocoon. Furthermore, a study reported in May this year highlighted an unsung role in pollination for thousands of non-domesticated moth species.

The work of pollination by bees is well-known as they are easily spotted flying in the daytime. In contrast, moths mostly pollinate at night, their hairy bodies transferring showers of pollen between the flowers from which they suck nectar. The researchers found that half the moths they captured were transferring pollen and that they acted as generalists by visiting many different kinds of flowers, including some that are untouched by bees.

Observing moths for yourself in summer is easy thanks to moths’ attraction to lights in the dark. By recording the moths you see like this you can also contribute to the conservation efforts to record and understand moth numbers.

Butterfly Conservation, the charity that hosts a network of county moth recorders to help collate records, also promotes nationwide butterfly and moth counts (the butterfly count is at the end of July and Moth Night is August 27-29 in 2020).

The charity has also developed an app (What’s Flying Tonight) to help identify the 900 species of large moth that can be spotted currently near you. Communal observation projects like this have acted as a warning system for the effects on moths from farming and street lighting, demonstrating the power of ordinary people taking an interest in the environment around them. For more information on all these resources we recommend mothscount.org.