I have a terrible problem this year with leaf miners. They're in
everything -- spinach and chrysanthemum, which isn't unusual, but they're
also in ranunculus and several perennials, all in different areas of the
garden. They're also in my greenhouse plants too.

I've been picking off the affected leaves, to no avail.

Anyone else noticed an abundance of this pest recently? Anyone have
suggestions on dealing with them? Are they are big pest or just a minor
nuisance?

Thanks.