A: With the West Nile virus going around this year, it is more important than ever to protect your kids from mosquitoes. For little ones who are not walking, just use insect netting. For babies over 2 months of age, DEET is very effective and safe if used appropriately. It should be used just once a day and washed off after going inside. For babies and kids of any age, Picaridin (the active ingredient in Cutter) is also safe and effective against mosquitoes--and you can reapply it safely. Oil of eucalyptus is approved only for kids over 3. Citronella is not effective.