For the second year in succession we have ants nesting in one of the garden waste recycling bins, which happens to be close to a cardoon plant that's hosting numerous small colonies of black bean aphids. These attract the ants because they secrete sweet, energy rich honeydew, the waste product of the sap they siphon from the cardoon.
In the image above and in the final image below you can see a feeding ant's swollen abdomen, rendered almost transparent where the pigmented plates of the abdominal segments have been stretched apart.