I have not tried it, but I just read about this remedy and I figure you guys may be interested given the amount of bugs in PR, specially flies
Get rid of bugs In a spray bottle mix equal parts of natural vegetable oil, champú and 9% white vinegar. Mix well and spray areas visited by bugs. Non toxic, kills mosquitoes, roaches, flies and other insects.
I just returned from a trip to the marshes near Savannah, Georgia and the locals recommended a product called No-Natz. It was made by a local fisherman and contains all natural ingredients (rosemary, lemongrass, coconut oil). I was really skeptical but it truly worked! I picked up a couple of bottles to bring home. I go to marshes to photograph frequently, and I've had chemical insect repellants damage my camera gear.
Articles to help you in your expat project in Puerto Rico