Choices of which I am aware in order of increasing weight.
Simple Bug headnet from various sources: 0.5-1.0oz
GossamerGear Bug Canopy – primarily intended for use in the GG SpinnShelter, but could be easily adapted to many other shelters: 3.0oz. Best service I’ve ever experienced from any company. GVP & GG bend over backwards to please. I’ve placed many orders from Glen & his company & EVERY transaction has been flawless. Ships immediately – often the same day. He may be away on the east coast sometime around May 10-16 if I’m not mistaken. Not sure who runs the show when he’s away.
EquinoxMantis: 4.5oz
Adventure16 BugBivy (double-check the name as I may be slightly off on the exact name): ~6.0oz with a nice flexible hoop to hold it off your face.
MountainLaurelDesigns integrated GroundCloth/BugBivy combo: 6.8oz-12.5oz depending upon size (1.0, 1.5, 2.0). Ron Bell at MLD will perform custom work for you at a small additional cost. Call & email him to discuss your specific requirements.
I know OR (Outdoor Research) & others make more traditionally shaped wire-hoop bivies totally out of bug netting. Not sure of the wt.
These are all I’m familiar with.