We only have two plants in the house - an orchid in the bathroom and a Ponsettia left from christmas. Neither of them has any sign of these insects (or any other).
There are litterally hundreds of these things, dead, mainly under or around wooden furniture.
This photo does not do justice to how many there are - we cleaned up yesterday and now \
We found a live one and it was more hopping than flying.
There are two large Rowan trees in the garden that have just finished flowering - could this be the source? Although I looked on the trees and saw nothing.
If you could get a better photo it might be possible to narrow down the source (e.g. is it a tree aphid?). It can be useful to see the cornicles sticking out the back end of the aphid - if it has any. That's how good the photo would have to be.
Without a better photo I can only suggest you search nearby trees and plants in the garden, although they may be dispersing from the winter host to the summer host.
from what I can see I wondred if it was something like this -
but I'm clutching at straws really
Ah, you've added some photos to your last post. Right, the one on its own is definitely an aphid (so, it hasn't come out of your furniture) but I can't really get much further than that. It's not one of the big pine aphids that people report on here occasionally. From the overall shape, the black/white legs, and length of the cornicles maybe Aphis sambuci is a possibility - it lives on elder and I have some on an elder in my garden at present.
But there may be other possibilities. Do all the insects look the same?