Our lemon shrub is a shambles.

There are countless cut and eaten leaves on our lemon shrub.  Upon investigation I can see tiny dry skins that look like leatherjacket skins on a few damamged leaves but only 1/4" long.

I've trimmed nearly all the affected leaves off the plant, it looks a bit denuded, but it may come through. Anyone out there any ideas what these pesky little critters are (or were) ?

Looking forward to your thoughts.  Cheers,  Tony.