What month do sparrows eat greenfly in southern UK?

Last year for the first time ever I noticed sparrows hopping all over my roses eating greenfly.

Right now my roses are becoming covered in greenfly, which is annoying as they are covered in promising buds. I tried scraping them off with one of those plastic between the teeth plaque removers, which is better than some methods I have tried. More importantly, I have some seedlings of hybridised roses that I grew from seed, which I have carefully removed greenfly from with a tiny paintbrush (the plaque remover might be not gentle enough for a tiny seedling?). Also, usually a bit later in the season, my Violas get killed by another type of aphid.

The neighbourhood seems to have a partially transient population of cats, which might influence whether the little birds feel safe. One large and beautiful cat came and went, and while he was around sparrows disappeared completely, and are now returning. Another cat has appeared, who seems more aggressive than many of them. Some of the local cats are very gentle, and once I saw two magpies swooping down noisily screaming at the gentlest of cats who didn't know which way to go to get away from them.

A major problem of trying to feed the little birds is that it attracts pigeons, which gobble everything (except aphids) and make a huge mess.

I don't know how best to attract house sparrows into my garden to eat the aphids on my roses. Maybe it is just too early in the season, or maybe the changing feline demographics affect them, or maybe they just get better pickings in neighbours' gardens and can't be bothered? I am starting to grow trees in pots, which might reach out to the sparrows better, if I make sure to place them where the cats can't reach. I have noticed in the past that this is the worst time of year for aphids, and something seems to keep them down later on, apart from the aphids that attack Violas.

 

Its primarily ladybirds and lacewings that eat them as larvae, so they have to find them and lay their eggs. The timing varies every year but eventually the population explodes. Lacewing larvae are so voracious theyll even bite humans! their eggs look like stalks with a bit at the end usually in groups of ~6

If you see none at all you can try blasting the aphids with a hard spray or spraying a little bit of soapy water on them.

I have seen a sparrow eating some aphids this week actually and some ladybirds here and there

 

So far this year the only greenfly I have come across have been on one of my potted Carnations.

 

Blue tits eat them also, but as usual waiting for them to get on and do the job usually means the damage is done before they get going.