Makers of DEET have long promoted the idea that natural mosquito repellants aren’t effective; but the CDC (U. S. Center for Disease Control) has approved lemon eucalyptus as an effective natural repellant. Moreover, it has no side effects, whereas DEET comes with all sorts of warnings as it is quite toxic. There are commercial repellants available (Repel is one that was mentioned, but this is not an endorsement, as I’ve never tried it). On commercial products, the label is more likely to read p-menthane 3,8-diol or PMD, but it’s the same thing.
Oil of lemon eucalyptus is made from the leaves of eucalyptus citriodora. You can buy the oil and make your own, using about 20-25% in a base of some carrier oil such as apricot or grapeseed oil. I like apricot oil because it makes your skin really soft.
Personally, I’ve been using natural repellants and find many different ones quite effective (Aromance is an Indian company that makes an excellent natural spray-on repellant). I’ve noticed that different people experience varying levels of effectiveness with any given repellant, which makes me think that it depends a bit on how it interacts with an individual’s body chemistry.
While I’m on the subject of mosquitoes, I’d like to mention that the best mosquito nets I’ve ever found are made by a Dutch company called Klamboe. Here’s there web address: <http://www.klamboe.eu/> I own a couple of different models, but my favorite is one that has a single point with a pop-open hoop. It’s absolutely the easiest one to put up I’ve ever seen. Unfortunately, they don’t seem to be for sale in India yet.