We visit four times per year, and every year for October. We have not had problems with mosquitoes on the boat in any anchorage (BVI, USVI, SVI). We have had problems with flies when we were anchored stern-to at Peter Island's Little Harbor last October.

We put but spray on when we go onshore. We're using Sawyer picardin-based bug spray these days.
http://www.consumerreports.org/insect-repellents/mosquito-repellents-that-best-protect-against-zika/

We have friends in the islands who have had Zika/Chikungunya/Dengue. We don't want it.

Cheers, RickG