It depends very much what the plant is, as many moth and butterfly species are dependent on just one type of plant. For example, the wonderful swallowtails need Fennel plants on which to feed.

Verbascums have a specific moth whose caterpillars only feed on them, as another example!

Every year a wee caterpillar eats the leaves of all the aquilegas and does not touch anything else. As already stated they are plant specific.

I'm glad I haven't met your little friends, Mg - I have a lot of aquilegias!

Currently we have Trichius fasciatus the bee beetle munching away on our siberian irises... very rare and we are delighted it has visited us.

How did you recognise it? Is it distinctive?

Very looks like a bumble bee until you realise it is a beetle - I've posted a pix of three of them having lunch :-)

I'll take a look. Thanks, Mg. :-)