I was at the Botanical gardens in Cambridge the other day when I saw these caterpillars crawling across this leaf. When you see caterpillars you immediately think of Butterflies, but in Britain the majority are in fact moths.
I recognised them as the caterpillars of the 5 Spot Burnet moth Zygaena trifolii I photographed this pair mating a few years ago. They are fairly common and one of the most distinctive of our moths and like Butterflies are day flying.
Many garden plants are moth pollinated, some such as honeysuckle are specialised for moths producing their nectar at night.