Chris, also that's probably one of the most disturbing nature videos I've seen. Very interesting though.

Many thanks for the replies! Yes they do indeed look like tiny wasps. I didn't even know these type of wasps existed. Very sad, would you think it's likely the other caterpillars are also infected?

Hi New to this site, so appologies if this has come up before. I'm currently frowning plants, radishes in particular which gained a population of what I think are small whites. One of which went into chrysalis a few weeks ago, I wasn't that bothered about the plants so I've just let them live on it....