Xmas aphids

It might be nearly Christmas, but someone didn't tell these Giant Willow Aphids, one of our largest aphid species. They are very active in my garden right now, which should be good for the robins and tits, but I haven't noticed them gorging themselves. It is possible that these aphids are too distasteful for the birds. It is stated that they have few predators, although Harlequin ladybirds have been observed eating them.