Henry Shires got there a long time ago. His whole business is designing tarps with netting sewn onto them. He gives away the pattern for his original homemade tarptent on his site.
http://www.tarptent.com/projects/tarpdesign.htmlAlso, on this very website:
http://www.backpacking.net/makegear/jones-tent/index.htmlAlso, on Quest Outfitters, one of many good sources of fabric and netting:
http://www.questoutfitters.com/patterns-tent,sleeping%20bag-cart.htm#Tent/Sleeping%20Bag%20Patterns
Seattle Fabrics has a bilgy pattern:
http://www.seattlefabrics.com/bilgy.htmlsome premade options from backcountrygear.com at left in sidebar:
http://www.backcountrygear.com/tent/Bug_Netting.cfmsome light examples of net tents designed to go with the SMD tarptents but could be used with a tarp:
http://sixmoondesigns.com/nettents.htmlLots to study and possibly replicate. Quest, OWFINC or Seattle Fabrics all have noseeum netting to keep out the buggies smaller than skeeters.