Aphids? On Acer tree

[seeyouyesterday]

So today I just noticed on the underside of almost every leaf of my Acer tree there are little black bugs, I think they are aphids? The tree is absolutely covered everywhere with them on the underside of it. I haven’t seen anything like it before. The only reason I got looking was that I noticed the leaves looked particularly small this year & when I felt them they feel a bit rubbery/sticky.

It’s planted in the ground, next to a Fatsia Japonica & next to the pergola which has a youngish Wisteria growing round it. It’s not in full sun, more in a shady spot. Currently around 7 ft tall. I’ve tried hosing it down but don’t think it’s done anything. What can else can I do? I think there are sprays but I’ll probably need 10 bottles! And I don’t want to be harming my other plants!

I dilute some Liquid Soap Flakes, put it in a spray bottle and spray the bugs. It doesn't seem to do the plants any harm, and it's not toxic to me. I always try to do any spraying in the evening after the bees have gone to bed. The soap works on blackfly and greenfly by damaging the wavy coating on their eggs and larvae, so I don't think it is toxic to bees, but I don't want to take the risk.