What are the measurements of the space? I wonder if it's too large for one of those adjustable screens you see in hardware stores. Otherwise, if there is not a ready-made screen to just pull out to the right dimensions, I'd fabricate a panel of wood or PVC pipe. PVC pipe would have the advantage of using the fittings to create an integrated tunnel at the top and the bottom, into which you could insert a tension curtain rod to keep it in place. If you got flexible plastic window screening, you could silicon caulk it to the PVC frame and then adjust the tension rods and insert it into place. For the gap between the screen and the building, I'd insert a length of self-stick draft-dodging spongy foam, which would fill that space and block bugs from entering.

Thank you, this sounds like a very hard project haha! ( for me at least)

This might help…. Get a spring tension rod, possibly a shower curtain rod?, that reaches from your wall to the frame of the screening. Hang thin, sheer draperies from it across the entire space, placing the rod tight up against the ceiling so that the fabric reaches from the ceiling to the floor. Although it is not a screen, it will block most/many bugs from flying between your spaces and it might add a bit of interest to the dividing wall. It certainly won’t be too difficult, or expensive, to do. Good luck!

I used a wooden batten at the top of the ceiling from wall to wall, glued in position with ”no nail“ cement, (no drilling) bead all around and smoothed. You could do the same, coming down from the ceiling to top of your scheen, does not have to be to big, i used 1/2 x 3/4 x L. Allowing the cement to cure, and treating the material and matching paint, again after drying, screw in stainless steel hooks (1/2) two at each end and equally spaced about 10-12 inch apart. Then using your choice of screening material, the size and colour, there is plenty of chose from. I used fencing sceening, which had come with some small brass hole studs, at one end, to hang up on to your s/s hooks, easily adding more hole studs matching size and pitch as required with a kit of hole studs, punch and pliers.

Thank you, I ended up finding a company that made a custome frame for me for about $400, they drilled into the concrete and secured it with screws. I wish I had known how to do it myself but you live and you learn! ( we also have very high winds at times so I was worried that glue might not hold up!)