I have solved the problem of ants building nests in the flowhive exactly as in the photo by smearing a paste of honey & borax on the surface of the cover - sides & back. While borax is poisonous to bees, they can’t get into the narrow spaces. Even with moats, various greases & cinnamon, I still found the ants (even different sizes) getting into the super. The bees seem to manage the ants in the brood box & in my standard lang hives, but the flowhive construction allows the ants to nest. The borax paste completely solved the issue, and does not appear to be harming the bees.
I don’t know, hey. To me that sounds like an ideal bee death trap.