I remember having seen at Hannover University, in the eighties, mass rearing of hoverflies. it was said they needed at least one cube meter space for flying, and were feed, among other ingredients, with hazelnut pollen. sorry not to remember more details.

Dear Paul,

Do you mean syrphid larvae? There are some artificial diets in textbooks but they are generally too complicated and expensive. Acyrtosiphon pisum is a preferred larval prey.

I do not prefer down-voting. Best way is to explain why was not suitable the comment in question.

Thank you for your answers about rearing larval Syrphidae.  I was really looking for a method which would allow year-round rearing of predatory species, on some kind of artificial diet.  It appears that there isn`t a diet for larvae other than fresh prey.  I shall continue my investigations and let you know what I find. 

Dear Paul

How is your work, can i ask you the rearing method of flies you are working with. I am interested in rearing Episyrphus ....regards 

Dear Amit,

At one time I reared blow flies, Phormia sp.  but never did rear Syrphidae.  It would be great if someone was able to develop a method for rearing these insects as they are a major pollinator that requires detailed study.

I hope you have success in rearing Episyrphus.

Paul