Do I have to apply repellent to my entire body?
YES
The blood meal is vital to the existence of biting insects, either for nourishment (as in ticks) or for the maturation of eggs (as in mosquitoes). Therefore, they will do anything to bite, and will seek out the slightest gap in your defences.
To avoid all risk of being bitten, it is therefore necessary to apply a repellent to all exposed body parts and to all those that might become exposed when moving. It is also necessary to remember to reapply the product regularly, not to exceed 3 times per day. When staying in an area that is at risk for serious diseases, it is also strongly recommended to wear clothing that has been pre-sprayed with a pyrethroid-based repellent. Indeed, 40% of mosquito bites take place through clothing.