Hoverfly laying eggs

I have green fly problem for a few month’s now in the glass house, I think i did’nt spray enough times to get rid of them.. I think my peppers and chillies will not produce any fruit now because they are all over the flowers…. But yesterday a hoverfly got in and starting to lay egg’s every where the green fly are… How long will it take the eggs to turn to larvae and would it be possible that they would eat all the green fly..