In article , Jeff
writes
Hi.

What insects will eat greenfly (without then becoming pests
themselves)?
I know about ladybirds, but are there any others?

Hover flies.
A hover fly can lay several hundreds of eggs on a plant and each larvae
will eat up to 400 greenfly during its life time.

I think that wasps also eat greenfly but am not 100% sure.

Some urglers recommend (swear that the problem disappears) dotting
those bird peanut feeders round the garden. The theory is that a bird
will have a coupe of caterpillars for starters, a few peanuts and then a
few dozen green/black/white fly for pudding!!
--
Jane Ransom in Lancaster.
I won't respond to private emails that are on topic for urg
but if you need to email me for any other reason, put ransoms
at jandg dot demon dot co dot uk where you see