Would think they are not as plentiful as the rainy season, We were there for 2 weeks end of November in a villa in the hills overlooking Long Bay and they were plentiful, somewhat of a nuisance , just have to spray every morning and in the evening. We liked the skin-so-soft wipes with Picaridin from Avon or the deep woods off if you don't mind the Deet Also found the mosquito coils from One Stop lite around the villa worked great. Still had a great time and no problems on the beaches during the day. Have a great time! Love the BVI!!!