No, that isn't the snowscreen. The snowscreen (on models that have it) resides in the air intake duct upstream of the air filter (the MAF is downstream). In my Jetta, it's in the small air tube part that runs between the battery and the inner fender and there's a 10mm nut that you have to remove in order to be able to pull it out. Presumably the Beetle is similarly set up in terms of intake tract.
Once you have it in your hands, you'll find that duct is actually two pieces, held together by two small screws. Pull those, and you get easy access to the snowscreen (assuming a previous owner hasn't already cut it out). Just "behind" the screen (toward the airbox side), there's a little spring-loaded door that opens into the duct. The idea is that if you're driving in a blizzard or similar conditions, the snowscreen keeps the snow/bugs/debris from reaching the air filter; if that clogs up enough to impede the engine's ability to breathe, the vacuum pressure from the engine trying to suck in air overcomes the spring and pulls that little door open, bypassing the snowscreen with warm air from the engine bay to keep you going.
In 2003 VW did away with the snowscreen and switched to an air filter that had a foam layer on the underside to get the same effect.
