Caterpillars are at it again…what to do?

In a section of my backyard, I have an L-shaped vegetable garden. In one half of the L, I have successfully grown tomatoes, capiscums, and chillies, all without any major issues with bugs. This part of the L is up against a fence. However, in the other half of the L, every time I start to get plants producing fruit or vegetables (sweet corn, cabbage, cauliflower, and now chilli), caterpillars seem to start taking great delight in feasting on my goods (this part of the L is more exposed).

I have a line of about 5 different types of chillies, some sweetcorn, and some onions (which don’t appear to be affected) in this second part of the L, that I don’t want to lose…and the last time I used some spray, it only seemed to amplify the caterpillars (with my cabbages, I saw a caterpillar attacking one, started spraying, in two weeks time all my cabbages were being attacked). I can’t remember what I used last time…any recommendations on what to use to get rid of the caterpillars? The caterpillars do not appear to be attacking any other part of my backyard, just this one small part of the L shaped vegetable garden.