We were in Cozumel last week and for the first time we encountered flies. Since I just like to sit at the table under the thatched roof while the boys swim and not get out in the sun....they were really a nuisance. They were everywhere. We were there just a few months ago (exact same table on the beach ) but it was a breezy day and this was not a problem. So I am seriously considering taking a couple of this little thin pest strips with me in December, just in case. I had heard the flies are worse on the other side of the island...but this is the first time we had experienced them on the tourist side. No other critters...just flies. (And not the kind that bite...just annoying)
I have been warned about the sand flies in Roatan Honduras. If you are going there be sure to use lots of insect repellant as the bites itch like crazy for days after. They are small and hard to see and sometimes you don't realize you're getting bitten.
We were there last week 10/12-10/18. We visited Key West, Cozumel and Belize. We did notice the flies were pretty bad on the beach at Nachi Cocom, but it didn't ruin our day. We also went cave tubing in Belize (a blast, by the way) and did get a few mosquito bites...and we were using bug spray. The only time they bothered us was while walking through the jungle...during the actual tubing it was ok. They were no where near as bad as they are on the East Coast. Have fun.