"I located additional information on this topic. The principal addition is the effective use of Oil of Lemon Eucalyptus [p-menthane 3,8-diol (PMD)]. Your article, and the follow-up by Robert Stone, does not cite Oil of Lemon Eucalyptus as a "natural" mosquito repellent."
Updated Information Regarding Insect Repellents (Excerpt)
[Repellents containing oil of lemon eucalyptus [p-menthane 3,8-diol (PMD)], a plant-derived active ingredient, are also registered with EPA. In two recent scientific publications, when repellents containing oil of lemon eucalyptus were tested against mosquitoes found in the US they provided protection similar to repellents with low concentrations of DEET. Note: This recommendation refers to EPA-registered repellents containing the active ingredient oil of lemon eucalyptus (PMD). “Pure” oil of lemon eucalyptus (e.g. essential oil) has not received similar, validated testing for safety and efficacy, is not registered with EPA as an insect repellent, and is not covered by this CDC recommendation.]
Thanks Heidi! I have the Cutter™ Insect Repellent which lists oil of lemon eucalyptus as its active ingredient. The product states that it repels moqsuitoes and ticks. I don't have any personal experience with the repellent and ticks, but it's highly effective against mosquitoes. The product isn't greasy or sticky, though it feels oily when you first spray it on. However, the odor is distinctive. I wouldn't say it's unpleasant, but it's noticeable. When I tried this repellent, all four of my kids asked, "What's that smell?" when they walked by me. Anyway, the active ingredient works and it smells different from DEET.
Photo: Mosquito on Human Skin, USDA