apparently they bite people with higher sugar diets, not sure if that's an old wifes tale or not. and also garlic is meant to help, you can try taking garlic capsules.
I dont think you get anymore problems with mozzies in menorca than you do anywhere else in the med
Our 8th year in Cala en Bosch at the beginning of July and up until 3 years ago i was bitten numerous times until i bought Boot's extra strength insect repellent. Its in a grey bottle and i've used both the pump action spray and also the gel and have not been bitten since. Mozzies love perfume and aftershave and are out in force in the early evenings. Also if you go into Son Xoriguer be extra careful as they are very common there. Not wanting to put you off because it is beautiful in Cala en Bosch but you do need to use the repellent. Hope you have a great holiday and let me know how you get on.