I think the Black soldier flies will need somewhere to lay eggs over the food. I think wrapping cardboard around the fly inlet under the cover might give them a place to lay eggs. How do you plan to complete their circle of life? Can you heat up PVC and bend/warp the pipe to be tighter to the sides. They might wiggle between the pipe and wall.
Discussion
There is corrugated plastic under the intake.
Ok. I see that now. I thought I read that if the holes are vertical it is more natural for them. I cut cardboard into 3 inch strips and then rolled it up like a fruit by the foot and wired it together. Gives a lot of holes to use in the same space as the flat surface.
That's a great idea