Who's got the munchies?

It's not easy to tell, but this is a one-year old passionfruit vine.

And this is its friend, about 8 months old...

The poor things are being munched to smithereens. :(

And the problem is, I have no idea what the culprit is. So far it has been a matter of elimination.

The passionfruit eater:

- especially likes tender young shoots (*sigh*)

- is not regularly diurnal- I have never spotted anything on the leaves other than two spiders

- is either quick to hide at night or an infrequent visitor- torchlight expeditions have yielded nothing

- is probably not a possum or mouse, as some of the damage is to one surface of the leaves only

- is not lured into a beer trap- so unlikely to be a slug or a snail?

-may be responsible for defoliating these bok choi seedlings and all my carrots and radishes that were in the vicinity...

I've been trying a variety of smelly deterrents, which may help a little, but I would love to know who my enemy competitor is!

The best our local garden centre has offered is "caterpillars" and a box of Dipel (anti-caterpillar bacteria) which I may yet crack open.

Any ideas??