What makes essential oils the best for insect repellents is that the scent will repel ticks, gnats, flies, fleas, and mosquitoes and offers more aromatic benefits. The most popular essential oils are cinnamon essential oil, melaleuca essential oil, and patchouli essential oil. Cinnamon essential oil is an effective insect repellent since it is well researched that it can actually kill mosquito larvae. Melaleuca essential oil counters flies, gnats, and tics. Patchouli essential oil not only has aphrodisiac properties, but it also aids in the repelling of bookworms, silverfish, moths, and mosquitoes.