The number of moths in the UK has declined by 28% since 1968. There are various causes, including use of pesticides and other changes in agricultural practices, destruction of habitat, and anthropogenic climate change. See https://butterfly-conservation.org/moths/why-moths-matter/mo...

> moths are just butterflies

It's more accurate to say that butterflies are a kind of day-flying moth, those belonging to the superfamily Papilionoidea of the order Lepidoptera.