We found mostly no-see-'ums, with some mosquitos and flies.
Islands we've been to:
* West End, Grand Bahama - VERY
* New Providence - some
* Andros - THE MOST, day and night [our worst memories in terms of no-see-'ums and best in terms of adventures]
* Exumas - very little (only on leeward beaches and in the evening- somewhat annoying during beach fires only)
* Crooked Island - some away from land, more closer to land
We have screens on our hatches and got a mosquito net for our companion way. It worked without problems everywhere (some no-see-'ums would get in through the netting, but not bad), except on Andros. On Andros for the first 2 days I was walking around everywhere in complete thermal underware (pants and a top) with gloves and a hat so that there was as little skin exposed as possible

. Then someone told us about Skin So Soft by Avon

(sold everywhere in Bahamas) . We slathered it on ourselves and on the screens. No-see-'ums went away.