I have a gnat problem, not fungus gnats, but the fly in your nose and ears gnats. Has anyone tried something to plug the ostioles? They don't eat much but cause souring. I was thinking maybe corn syrup or veg oil or the like. I really don't want to make and attach a bunch of organza bags. Any suggestions?

Beeswax might work, never tried it...

Petroleum based chap stick (non food-non coco butter based) if you like you petrochemicals. Never tried that either, but you could try a coco butter based lip balm if you dare.

Gnats do not bother figs. Are you sure they are not fruit flies? The spotted winged drosophila causes spoilage of healthy fruit and doesn't need an open eye to do it.

Species dependent, some say they mostly cause spoilage via cracks in the skin and the eye:

https://figs4funforum.websitetoolbox.com/post/fruit-flies-and-figs-yaks-7147112


http://lee.ifas.ufl.edu/Hort/UsefulLawnandGardenResources/FigFruitFlyupdate2008.pdf

It is often recommended to brush olive oil on the eyes of figs to speed ripening.  I suppose it would have the additional effect of keeping out insects.  Beware, blocking the eye with anything I assume will effect ripening and flavor somehow.

Where I am olive oil attracts ants, would try a non food source.