DEET is very dangerous!
watch out how you use DEET. yes, it is the only really effective way to repel the mosquitos. but be careful.
it is not even supposed to go on your skin. you're supposed to apply it to clothing only. of course, everyone puts it directly on skin. small children should not use DEET.
there are cases of people becoming very ill from constant re-applications to their skin while camping... and not bathing regularily. over 3-5 days, they become toxic and can suffer kidney and liver failure. of course, i assume people will bathe while in the DR!
this substance was banned in Canada and then re-introduced in a lower concentration.
you're much better off to just use some common sense. the little critters are out in force and hour before and and hour after sunset. wear socks and light pants and maybe a dress shirt. or just stay inside until the worst of them has passed.
if you live in a mosiquito area, consider getting a propane "trap" that attracts mosquitos and finishes them off. they take about two weeks of operation to become effective and can cover a large area. i live near alot of wetland areas and our neighbours swear by these. not 100% effective, but close.