The second biological control I released in my attack on the aphids were Aphidius ervi wasps. There were ordered from Biobest. Parasitic wasps are SO COOL (this is coming from a girl who is terrified of yellow jackets and hornets).
As their name implies these wasps lay their eggs in aphids. When the eggs hatch the new wasp goes through all it's juvenile life stages inside the aphid and eventually emerges as an adult, thus killing the aphid. The dead aphid is called an aphid mummy. You can see A. ervi in action below. The aphids don't even seem scared. Why aren't they running away?
The wasps come as eggs in aphids and are packed in buckwheat hulls (that's what you see in the photo below on the left). I placed saucers of buckwheat and aphid eggs around the greenhouse and left them there for a week. I had high hopes of seeing something exciting.
Alas, I have yet to see a wasp. They are really small and they don't sting. Other greenhouses on campus use these wasps to control aphids, which is how I took the picture on the right. See how small they are? If you're eating you might want to swallow your bite before watching the video below. Pretty cool huh?