Decks, Patios, Porches and Docks - Screened Porch/deck help

I have to do some buttoning up on a screened porch, but along the bottom of each screened section there is a 3/4 to 1 inch gap (I'm assuming for drainage purposes) which is stuffed with a brittle black, fiberous material. I'm assuming this is for bug-blocking, but I've never seen it before. I've been asked to make the porch bug-proof, but I'm not sure how to proceed with this bottom section. Is this material a common install, or a builders cob job? The black material resembles those nylon scrub pads, or certain types of filters (furnace, a/c, etc.). Any suggestions??? Thanks

Sounds like a homeowners attempt at bug proofing. What type floor does it have? If it is a deck, have you addressed the joints in the deck boards? The gap on the bottom of the screened area can be attacked by ripping a 1x board to an appropriate height with a bevel at the top and installing it with a finish nailer. Bug "proof"? Ain't no such animal.