The AntsCanada Ant Forum's

With the size of Camponotus (Pennsylvanicus in my case) is there any need to glue down the glass or is letting it sit on its own enough?

I would glue it just to be safe.

Applying a bead of Elmer's school glue around the perimeter is a good idea. I have seen ants push small grains of sand or other objects up into that small space between the glass and the formicarium and over a period of time it slowly raises up the glass. Crazy!

Just enough to tack it down, while still being able to pop the glass off the top for cleaning if needed?

Yup, that should work.