Does citronella really keep mosquitoes away and is there money in growing it for oil?

Citronella is an aromatic grass grown for citronella essential oil, which is genuinely used in mosquito repellents, candles, soaps, sprays and cosmetics, so the demand is real but the price is driven by an industrial oil market that competes with cheaper imported oil, which keeps rates volatile. It is a hardy perennial grass, drought tolerant, suited to warm humid climates and light well drained soils, and gives multiple cuttings per year over several years, much like lemongrass. Oil recovery is low, typically in the rough range of around 0.5 to 1 percent of fresh grass, distilled from the freshly cut leaves. Whether there is money in it depends on your grass yield, oil recovery, and the market oil price, all of which vary, so treat income claims with caution and build your own number from a confirmed buyer rate. The honest warning with citronella is price competition from imports, so secure a buyer and a realistic price before committing a large area. It needs a distillation unit, so share or custom-hire a still rather than buying one as a small grower. It is a reasonable crop for hot, marginal land if the oil buyer and distillation are sorted first.