A new friend...

I've been trying to save lots of sweet pepper seed this year, which requires something like organza bags to isolate the flowers and prevent cross pollination. Just yesterday I was taking one of the bags off and noticed a lot of these red larvae underneath a few of the leaves. One of the problems with bagging a plant is any pests on the leaves under the bag will proliferate with wild abandon. As is the case with hot summers, aphids have been a problem in the greenhouse and it seems they had been having a party under the organza bag, until a helpful friend turned up. 

This year in the greenhouse I've seen hoverfly larvae, parasitic wasps, ladybirds and minute pirate bugs, but I'd never seen bright red larvae before. These are larvae of a predatory midge called Aphidoletes aphidimyza and they feed on over 70 species of aphid. They paralyse the aphid by injecting a toxin in to their legs, then suck the juice out of the aphid's body. An adult midge must have squeezed through the bag opening, or had already laid eggs in an aphid colony before I put the bag on. You can see some dried out aphid bodies in the photo.