something's nibbling at my basil

Hello fellow allotmenteers. Here's a new brain teaser. I've planted about 15 basil plantlets raised from seed, in pots still in my backyard, the plan is to take a few to the allotment. Anyway, holes the size of sequins have been appearing in the leaves of some and it's spreading. I don't think it's slugs as there's no slimy trail, maybe the beast is airborne? Any ideas would be welcome. In the meantime I've brought most of the plants indoors.

Just had another look and found the culprit. It's a caterpillar, only 1 cm long and very skinny and the colour blends totally with the bright green of the basil. I squished them PDQ. I suspected a climber/ flyer because the stems were untouched. I'll be doing regular checks. Also noticed greenfly had already started up.
There's no let up in this battle is there? :happy: