They have suddenly appeared in lage numbers, emerging from their larval forms - the sycamore leaves are covered in these - to feed off the huge number of aphids present. Thus they out-compete the native ladybirds they don't actually eat.
And this is why I'm just about seeing more harlequins than any other species at the moment, when a few years ago, the native 7 spot was probably most numerous.
|Native black variant two spot ladybird on the front door
|Harlequin type 1
|Harlequin type 2, seemingly sporting the sign for Aries on its carapace
|Harlequin larval husk
|Another larval husk