The best repellent for your child is to avoid exposure. Wear long pants, tuck in shirts and wear socks. Mosquitoes can bite though thin clothes and spandex.
Something to remember about repellents is that less is better. They are chemicals. Never use a repellent with over 10% DEET or that is above 30% flammable. Don’t put it on baby’s hands; they can get it in their mouths. Wash off the repellents as soon as you come inside. Do not use a repellent and sunscreen together, they will degrade each other. Try to encourage outside play during the day and inside play at night.
Insects bite by smell so avoid scents of any kind such as lotions or perfumes. The proper application is one to two times a day and no more.