Though often perceived as an environmentally-risky practice, biological control of invasive species can restore crop yields, ease land pressure and contribute to forest conservation. This paper illustrates the positive impacts of biological control using the cassava mealybug Phenacoccus manihoti (Hemiptera) as an example. Cassava is a key food, feed and fiber crop grown on around 4 million ha in tropical Asia, where use of a parasitic wasp lowers crop losses, restores farm profitability and slows deforestation.