Well, After reading these posts, and then doing even more research on Tripadvisor and other cruise and traveler sites, this is the sum of what I've learned about these critters that leave intense itching:
1. Sometimes they are not a problem, and sometimes they are. Some seasons might be worse than others.
2. They are picky biters! Some people they won't bite, and other people they bite alot.
3. They love salt on your skin. So IMMEDIATELY put on protection immediatly after leaving the ocean water.
4. Avoid damp sand near the water.
5. The tiny critters cannot fly against the wind. So breezy days are your friend!
6. They suffocate in oils or other "goop" people put on their skin. So slathering this goop on helps ALOT.
7. Insect repellent such as Backwoods or other 100% Deet helps ALOT.
8. You can read up on all the goop people put on their skin, such as different types of oils, and Avon skin so soft.
So this is what I'm going to do:
1. Not worry about the season, since I can't change it. But I'm glad I'm going in early spring!
2. Have goop in my swimsuit button-down pocket and put it on IMMEDIATELY upon walking out of the water. Then find a place to rinse off and then goop up again.
3. Put Backwoods OFF ON TOP OF THE GOOP.
4. Which goop will I choose to use? I'm going to use that which is sold locally, apparently "all over the place" locally for the purpose of keeping sand flies at bay: Sunscreen that has cactus juiice as it's base. But I'm not going to go shopping for the stuff while I'm in Roatan. I want to put some on before I get off the boat, or at least before I get off the pier. So I will buy at least one container online, prior to my cruise departure.
5. Some people get bitten because they forget to keep the goop or oils on. I will make it a point to stay slippery goopy and constantly put Backwoods Off on top of it. Constantly. Yes, it's bad for my body, but only for a day.
6. I will have clear aloe ready back at the cabin on the ship. Maybe some .1% Hydrocordisone acetate or cream, also.
7. I will notify the parents of the problem of sand flies if I happen to see a baby playing in the sand, and the baby appears to be with a tourist family.
After all this preparation, I am going to make VERY sure that I enjoy my time in Roatan. Apparently, it's such a great place to be that many people keep going back to visit, and even to retire there, even though they've been bit many times!