I had them too. I was told it's a tomato horn worm caterpillar. They stripped down all of the oregano which was in a 5 gal container within 5days.

All I was told it would turn into a hawk moth. I didn't look in to it though.

Tobacco hornworms (the most common hornworm found on tomato plants) have a pink or red horn.

Was this hornworm actually eating the buddleia? If so, I don't know what it was, but it was probably traveling to go underground somewhere and make its pupa. It's most likely a pawpaw sphinx - I think I can see the sand papery area on the back of the head.

Sherry