Yes, Citronella keeps mosquitoes and other insects away when used topically in a carrier oil. Research suggests that Citronella Oil for mosquitoes remains effective for up to 3 hours. However, this may be affected by air temperature and humidity as well as how often you sweat. When using Citronella Oil as a natural bug repellent, we recommend reapplying as soon as you notice the aroma has begun to fade.