USA Today has a great report out on the effective ways to ward off mosquitoes and the sometimes serious illnesses their bites can cause. And, the best preventative does NOT include rubbing your skin with Bounce dryer sheets, eating garlic, or downing vitamin B.
My Take?
This is a great article for all parents and grandparents to read. The bottom line, the best preventive treatment is one of several commercial repellents — “an unloved group of products that can be stinky and sticky and, if used incorrectly, potentially toxic.”
“But using them is worth the relatively small risks and the ‘ick’ factors. All it takes is one bite” to be infected with West Nile virus or another mosquito-borne illness.”
According to the Environmental Protection Agency, these repellents do work, to varying degrees:
• DEET (N,N-diethyl-toluamide), a chemical developed by the U.S. Army in the 1940s.
• Picaridin (KBR 3023), a more recently developed chemical.
• Oil of lemon eucalyptus or its synthetic cousin, PMD (p-menthane-3,8-diol).
• IR3535, another relatively new chemical.
• Permethrin, which can be used on clothing, camping gear and other objects, but not on skin.
At its website, the U.S. Centers for Disease Control and Prevention says skin products containing DEET or picaridin “typically provide longer-lasting protection” than the alternatives. 
But the CDC also says oil of lemon eucalyptus works about as well as low concentrations of DEET. 
Products with 5% DEET protected for about 90 minutes, and those with 24% worked for five hours, according to a 2002 study in the New England Journal of Medicine.
The American Academy of Pediatrics recommends that parents consider how long a child will be outside and choose a concentration of DEET (up to 30%) that will last that long. “A 10% product is going to protect a kid for two hours, and often that’s all you need.”
The group says DEET is safe for children over age 2 months; oil of lemon eucalyptus products are labeled for use by children over 3. 
The CDC also advises:
• Apply only on exposed skin, not under clothing.
• Don’t apply to cuts, wounds or irritated skin.
• Wash treated skin when you return indoors.
• Don’t use products combining repellents and sunscreens; sunscreens should be reapplied frequently.