Well, new to me. I took a couple of photos earlier this week of a strange phenomenon on my bolting broccoli. There were two little nets of yellow... eggs?... No, too big for that... pupae? Each net had one very large but crook-looking Cabbage White caterpillar next to it. I fed one caterpillar to the chooks but left the other in place to see what would happen. It's disappeared now too.
I knew that some parasitic wasps lay their eggs inside caterpillars, but couldn't figure out what was going on here. Then I read Lyn's post today, and now I know that these are indeed pupating parasitic wasps, small Braconids. More information here about them.
I have seen quite a few varieties of wasp in my back yard but haven't been stung by any yet. Once I saw an enormous wasp fly onto my washing line. It took a large bite out of the Cabbage White caterpillar it was holding. Left a bit of green goo on the sheet it was on, but I forgave it immediately!
Apart from their interesting behaviour, there's another reason to have a good look at the wasps in your garden, and that is to make sure you aren't harbouring the European Wasp (if you are Australian, I mean). This page has good pictures of the wasp and its amazing nest, but far too many capitalised words. If you happen to find a European Wasp nest, leave it alone (they can contain up to 100, 000 workers, each with a reusable sting!) and contact your Council for advice.