When I play Eotu I notice that the area around the entrance is a bit unprotected. I think that to protect the entrance better, there could be a pheromon / marker patrol (with the things I've sketched in the picture) keeping the area around the protected entrance protected. In the image I made to give an example, the player would have to position 3 or 2 points (dark blue dots) in a limited area (inside of the gray circle), the ants placed in the group of patrol would go from point to point to the entrance (light blue lines) keeping the area around the protected entrance and increasing the viewing area around the nest if the fog of war is active.
I put in the drawing a purple dot for the ubercreatures, just to be able to identify more easily on the minimap.
I hope you're not too confused.