I bought the screens for the furnace flue and water heater door and
did much the same as OC in the bottom photo but I used a hot glue
gun instead of duct tape.
In my case it's to try and keep out the #@%&*! lady bugs that flock
to any crevice or tiny opening in the fall.
I'm still finding them in my home and my trailer
After 6 seasons of no problem I found a wasp nest in my trailer bumper
alongside my dump hose this fall. I hot glued a scrap of nylon screen
over the holes in my bumper end caps too.