I take it that you are talking about mosquitoes and if you are they are not found on cruise ships because of the air con. and because they get sea sick. If you go ashore, however, you can get bitten so if they generally make a Bee-line (sorry) for you then yes wear a repellant. I would suggest you go to RCI' s web site and ther you can sign in and look at not only your cabin but all the other cabins as wel. You can also book excursions, fill in your Seapass and find out all the other answers to questipons you no doubt have....Heathe.
I have only ever found one that worked for me and that sort of worked for me and that is only available in Australia. However despite normally being eaten alive but whatever the local creepy crawlies are on land based holidays, I've never hd much trouble when in the Cribbean on cruises, occasionally just 1 or 2 bites. Suppose if you were to go deep within a rainforest you might be more prone to getting bitten, but otherwise, i'd say don't bothe.
Thank you heather i have been to cuba last year and havent been bitten due to wearing a very effective repellant so i think going ashore ill use the same on my carribean cruis.