This chapter summarizes the main features of orange oil as a biopesticide. Orange oil is an essential oil (EO) produced by cells within the rind of the orange fruit, which is extracted as a by-product of orange juice production by centrifugation due to numerous domestic, industrial, and medicinal uses. Orange oil is highly effective in killing and repelling entire ant and termite colonies, preventing reinfestation. Indeed, orange oil showed both contact and fumigant toxicity, dissolving and dispersing the pheromone trail left behind by ants so that new ants cannot follow it back to the original nesting spot. The broad spectrum of action of orange oil will also allow postharvest application of these new biopesticides, to enhance the storage of produce and valued crops, by preventing pest-induced deterioration. Orange oil terpenes, indeed, are not stable and are easily oxidized and deteriorated when exposed to high temperature, oxygen, and humidity, namely, the conditions typical of open fields.