Country diary: A host of treasures in my moth box | Jan Miller

Through wet grass on an unusually warm morning this “year without a summer”, I approach the treasure chest of my moth trap. Underneath the Perspex lids, I can see many live jewels; mother-of-pearl, swallow prominent, brimstone, copper underwing, phoenix, flame shoulder and footman. Then, amazingly, as I carefully lift out the egg-box hiding places, two huge pale-blue rarities called Clifden nonpareil appear.

A lot has been said about how few butterflies and bees there have been this summer. With about 2,500 species of moth native to the UK (compared with 60 butterflies), there always seem to be more moths around, but we won’t know if they are faring better until the records come in. Unlike butterflies, they don’t need bright sun , and many species need moisture in the air. As a result, some are spreading north from Europe with climate change faster than others, due not only to temperature but to increased rain, including once-scarce moths such as scarlet tiger and Clifden nonpareil, both of which need a damp habitat.

Finding a Clifden nonpareil ( Catocala fraxini ) has long been the dream of many naturalists, due to its large 10cm wingspan, pale blue pattern colouring and its scarcity. It became extinct in Britain in the 1960s and was later only seen as a rare migrant from the continent. But since about 2005 it has been seen more often in the south, spreading up to north Wales and Yorkshire by 2023, with early sightings now in Scotland.

Related: ‘Monster of the moth world’: why Clifden nonpareil is ultimate prize for collectors

The broader picture with Britain’s moths is not good – 40% of our species have seriously declined since the second world war. There are many reasons for these changes. All-night light in towns makes leaves too tough for caterpillars. Industrial pesticides 10,000 times stronger than DDT are still used. Drugs for fleas and intestinal worms in domesticated animals are getting into the soil and watercourses.

But moths can be surprisingly adaptable to change. Moth larvae are often more polyphagous (eating a larger variety of plants) than butterflies, and many feed on native trees. Allowing grass and wildflowers to grow may attract adult insects, but if mown too soon can simply trap them where they cannot breed and overwinter. More meadows and corridors of trees are needed to wind through our cities and countryside. And wouldn’t that be great for overheated and polluted people too?

• Country diary is on Twitter/X at @gdncountrydiary

• Under the Changing Skies: The Best of the Guardian’s Country Diary, 2018-2024 (Guardian Faber) is published on 26 September; pre-order now at the guardianbookshop.com and get a 20% discount