You could try this stuff.

It would be useful for all different scales.

http://cgi.ebay.co.uk/WINDOW-MOSQUITO-NETTING-INSECT-FLY-MESH-NET-SCREEN-BLK-/330433673555?cmd=ViewItem&pt=UK_TravelTickets_Accessories_RL&hash=item4cef61b953

http://www.pestfixers.com/images/stockimages/106.jpg

I have some of this somewhere,its material and the gaps are little sideways squares and the distance of the gaps are about a 1.5mm .