Thanks - someone just sent me an email with the same thing - so it's a positive ID. Not a good moth. I hope the tree frogs get it. CT

Top image: Try looking at the skippers, either the cloudy-, sooty- or dusky-wings. There should be enough pattern in the photo to match it up in a guidebook for those few skippers. Bottom image: The common name is "chickweed geometer" (sounds like monitor--is this a local name?), or "chickweed moth".

I believe it's a Manduca rustica or Rustic Sphinx. Big uns huh?

When we were young, my sister and I used to keep caterpillars on their foodstuff in various homes that we concocted till they pupated, then we watched them hatch and released them. They are as you say, in most cases very plant specific. Sadly, it's reported that many types of the UK's butterfly population are now in decline. Most likely from overuse of pesticides or in some instances their food sources are being depleted by various means. I grow several flowering shrubs and perennials in order to attract them to my garden but this year I've definitely noticed there weren't as many around even of the common types, and that was despite the nice summer we have had. Gill