Good Flies?

[KeaCassella]

I read somewhere that I could purchase some maggots from flies that eat other flies maggots. I am interested in getting some and now I cant find any info on it. Can anyone point me in the right direction please?

 

[Mattemma]

Pretty sure it is a predator wasp.
http://www.arbico-organics.com/category/fly-control-program