What's been damaging my leaves?

[GardenFan]

If the hairy munchers do manage to take hold then a quick dust of derris sorts them out (and any remaining egg's). It's non organic in the organic sense but I have yet to see anything other than a white want to climb inside my cabbage (where a dusty death awaits). Not sure what salt water could do to the sodum level in the soil but worth a try as well.