You may be able to buy a can of OFF! in Grenada ,which has either an orange coloured cap or a dark green cap(Deep Woods OFF).This is an american product and may be quite expensive but it served me well when i lived in the West Indies! These repellants contain DEET and i think 50% is the strongest available and I always used that one. You can buy a similar one at the airport or in UK call "expedition 50 "I think. A roll on and a spray are both useful. However, beware of spraying near anything plastic as it will melt! I have often has the adverts from a plastic shopping bag smeared on my leg!!! You can also eat marmite or take Vit B12 before you go for about 2 weeks.The smell you give off is a turn off to mosquitos apparantly! My husband is never bitten. Leave off the hairspray and perfume too as they attract all insects! Citronella based /light citrus perfumes are the best for the tropics, or even Lavender.

I can also recommend going to Patrick's Restaurant , if it is still there after the hurricane, just south of the harbour of the capital St Georges. He has a tiny house and serves a set menu of tiny taster dishes which are absolutely delicious! The green banana salad is to die for! You used to need to book as it was so popular and very traditionally Caribbean!
Also the mini buses are an excellent way of exploring the island .They used to run about every 3 minutes past our hotel and we loved to visit La sargasse for a day on a different beach. Excellent value!
The Nutmeg products are unique to Grenada and the spray for muscular aches and pains has been very useful!!
Happy Hols!

Bens 100 has 95% deet.
xx