They pretty much stay on the underside of leaves, even through Winter & take cover under any dead bits. As they're an American import even ladybirds don't do much good so it's just chemicals to kill them off really. The RHS has a list of suitable insecticides if you Google 'RHS lupin aphid'.
I had masses of the beggars last year & ended up using a pump up sprayer with water & a drip of washing up liquid daily.
Good news is my plants are coming back fairly strong this year despite them. Maybe the plants build up their defences having been attacked once but there's not much sign of the aphids this year

Yet, Darren... I've given up on lupins for this reason, same as lilies cos of lily beetle, both of which make what should be a low maintenance plant very high maintenance indeed...

So I'm wrong then Bamboo? Not sure what your point is?
Also disappointed that you didn't choose any toms in my fun sweep😭
I offered a guilt free opportunity to guide my gardening & you, of all people, didn't put your oar in?

Same here Charnwood. My 3 year-old lupins in a pot are covered in the little devils every morning, despite my spraying with washing-up liquid in water and squishing hundreds. It hasn't happened in the previous years. Thankfully, they haven't attacked my newly-planted annual lupins yet and i think I might bin them before they do. There are only 2 of them in the pot so it's not a lot to give up.

No, of course you're not wrong Darren, dunno why you think I meant that; you know as well as I do that if you had been wrong, I'd have said so. Its just you said there was no sign of them this year, so I responded with 'yet' meaning not yet, give it some time, that's all... if I had access to emojis, a smiley face might have indicated it was a joke I suppose.

As for tomatoes, I'm strictly educated and practised in amenity horticulture, really don't grow veggies, not even toms, and though I inevitably know some stuff about veggie growing, others on here know far more than I do about that side of things. Which is why I didn't partake in your quiz, I wouldn't know a good tomato from a bad one, I just buy the ones I ike at the supermarket, thanks! We all have our specialist areas, don't we...

so far I haven't any lupin aphids but its a bit early for them here. I usually just squish them as and when I see them. certain I have seen ladybird larva feeding on them and some parasitic wasps laying eggs in them . gross but nature in all her glory.