We cut and sewed some mosquito netting to fit around the edges of our dodger and Bimini. I attach it at the top using powerful small refrigerator-magnets on each side of the fabric, and we added drapery weights to the bottom perimeter seams. It is very effective, and we also use it underway on the rare occasions when we’re attacked by biting flies (seems to happen about 2 or 3 times a year in southern New England, I think it’s associated with hatching events on the water).
PS - after research the cheapest netting was found on Amazon sold as garage door mosquito screens (for people to use their garage as an indoor/outdoor space).