Like many places in the world, Mumbai has a growing mosquito problem. Mosquitoes are vectors for diseases like malaria and dengue fever. Typically, authorities try to control mosquito populations by spraying insecticides, but increasingly, the insects are becoming resistent to them. A start-up based in Mumbai's Dhavari district, one of the world's largest improvised settlements, where dengue fever is rife, has come up with an easy-to-handle, eco-friendly oil-based trap which works by interrupting the insects' breeding cycle. The traps are now being widely tested in the district. Together with other strategies, such as preventing the development of stagnant water, and a government-funded interactive awareness app, the traps could have the potential to ease the situation and lower the numbers of those contracting dengue and malaria.