A picture from last year when the Black ants were swarming. The other inhabitants of the bin don't seem to mind the constant activity of the ants.
No interactions present.
To get black Lasius to species you need to use a microscope, or at least a lens. If you have not done that to exclude L. platythorax, L. alienus, L. psammophilus, and L. fuliginosus you can't say "as sure as I can be" to L. niger.
But Mydaea, I am as sure as I can be that: 1.They are ants
2.They are black.
But that does not make them Lasius niger. There are several other species of black ants, and not all of them are even Lasius.
Lat/Lng: 50.7, -3.7
OS grid ref: SS8300