I am in part of the country where there is a lot of Lyme disease and now there is a new tick born illness in the area: http://www.todaystmj4.com/news/local/126725658.html. So, I use the proven DEET. Even though I stick with DEET it does look like eucalyptus oil may be a decent alternative, if you aren't sensitive to the oil. There is some research showing its effectiveness in repelling mosquitoes. I would really like to see some good research its use in repelling ticks as Lyme disease and other tick borne illness is such a growing problem.