These little creatures – about the size of a pin-head – are sitting on a leaf of our grown-from-pip grapefruit tree.
They look almost cute, like tiny flattened mice, but they’ve got their mouthparts well stuck into the central vein, sucking sap.
I’m not sure how much harm they’re doing; the spider mites are probably worse. But they’re making the leaves unpleasantly sticky with their honeydew.
One way of getting rid of them is to pick or rub them off by hand, wiping the stove dust off the leaf at the same time so as to kill two birds with one stone. But the plant’s nearly two metres high and two metres wide and has a lot of leaves so it would be a bit like painting the Forth Bridge.