Tiny spherical "greenfly?" on violas and other plants.

@Balc I am not sure if I am doing it the best way, but it does seem to work. I haven't been troubled by aphids at all since they were plaguing my plants up to about June when I started using the Erigeron water. I just put the trimmings of the Erigeron karvinskianus (Mexican daisies) in a trug bucket, fill it up with water and then a few days later strain it through a sieve into another bucket to pour on the plants with a jug. I have some now that I have been using for a few weeks, I just keep topping up the water then squeezing and swishing around the Erigeron. Since I began I have only changed the Erigeron once, and put it in the compost pile, and that probably wasn't necessary. It is really just soaking the Erigeron karvinskianus in water, and the soaking water seems to work to get rid of aphids/greenfly even after a couple of days. It could be that it is better to soak it more long term, but I haven't had a problem with it either way. Your experimentation could be better than mine.

Erigeron karvinskianus needs trimming anyway to help it produce more flowers and keep it tidy, and it grows back very quickly. It tends to self-seed too.

I have tried ladybird (last year) and green lacewing larvae with very little success, and my garden is full of spiders who might be helping, but since using the Erigeron karvinskianus water in June my aphid/greenfly problem disappeared suddenly after being a huge problem.

 

I think the clue is in the Fleabane name. Native plant traditionally burnt indoors to control fleas.
https://www.plantlife.org.uk/uk/discover-wild-plants-nature/plant-fungi-species/fleabane-common