You're growing Cannabis, which draws literally every sweet-sensing pest.

Funnily enough, my weed is pretty much the only thing (and chillis) that isn't much affected. The willow is the worst one, and the pepino second.

Those things on the underside of the leaves you posted are Ladybug larvae, and they are GOOD.

Those larvae pictures are already a bit older, maybe two weeks? They probably got killed by the ants or wasps, because I rarely see them around anymore.
I also rarely see any other aphid eating insects anymore, only ants and ants carrying carcasses :(