Citronella is the Answer!
There are a lot of chemical sprays in the market, mosquito repellants, etc. But the best that I found is this Citronella Spray. It contains no harmful chemicals but just citronella essential oils and ethyl alcohol.
"Spraying citronella into a room will inhibit the growth of bacterial colonies. It will clean the air and neutralise mildew, cigarette smoke and all disagreeable odours. It will drive mosquitoes and other insects away." This is what this product claims to do.
We have been using this for several weeks now and true to its claim, it drives away mosquitoes and other insects like ants and cockroaches. Now we don't have to use chemical based sprays anymore.