Revenge to the killer caterpillars...

Brassicas are high-maintenance. I mean you can plant out a whole patch of silver beet everything runs smoothly, but Brassicas... oh boy, do they ever need some protecting from those infernal cabbage whites!
They're fine in the garden for the winter sowings because the white's simply aren't around. But from late Spring onwards it's virtually impossible to get your kales, cabbages, and broccoli through to harvest without some form of protection.

I don't like to use chemicals, like Derris dust. I would be OK with genetically modified Brassica's, transformed with a Bt gene to express itself in the young plants (killing newly emerged caterpillars at their first wee nibble), but in New Zealand I might be alone on this one. Certainly GE Free NZ and Soil & Health wouldn't share my feelings that these plants would be totally OK to human health and the environment! A good old-fashioned cloche could do the job, or caging the plants in a frame covered in bird-netting to keep the butterflies from unloading their round cargo on the young plants.

Must build something like this for next year.

For this season I've employed another method, which involves hand-plucking caterpillars and feeding them to the chickens.... not terribly effective in preventing damage, but revenge is a dish best served wriggly...