They are big aphids that often congregate in their hundreds on older lupins. I pull mine out every two years for this very reason. They are horrible and if your plant is in its third year or older I would pull it out as they destroy the plant. I didn't find hosing them off helped.
They only prey on lupins but apparently ladybirds don’t eat them. I go out every day and knock them off the plant, I find it quite good fun to be honest. Hold the flower in one hand then knock the stem and behold a little rain of aphids! My lupins grow next to a path so they fall on the slabs and I squish them underfoot. Funny thing is there is another clump about 6 feet away no aphids at all!
I knock them off with the hose pistol, pretending I'm john John Wayne.
They are a nightmare but like others, I have a lupin in a bed infested, and a lupin in a pot 6 inches away that's absolutely clear. I like lupins though, so I'll live with it....
Don't give up hope. I had massive infestation of them last year, twice daily round with pressure sprayer full of soapy water, little effect really, they kept coming back. Caused all the leaves to wither and the flower spires to look pathetic. But, the plants have bounced back this year and look lush again, and no sign of the grey horrors as yet... there, I've hexed mesel now.
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They are a nightmare but like others, I have a lupin in a bed infested, and a lupin in a pot 6 inches away that's absolutely clear. I like lupins though, so I'll live with it....
I had massive infestation of them last year, twice daily round with pressure sprayer full of soapy water, little effect really, they kept coming back. Caused all the leaves to wither and the flower spires to look pathetic.
But, the plants have bounced back this year and look lush again, and no sign of the grey horrors as yet...
there, I've hexed mesel now.