A kairomone (a coinage using the Greek καιρός opportune moment, paralleling pheromone) is a semiochemical, emitted by an organism, which mediates interspecific interactions in a way that benefits an individual of another species which receives it and harms the emitter. This "eavesdropping" is often disadvantageous to the producer (though other benefits of producing the substance may outweigh this cost, hence its persistence over evolutionary time). The kairomone improves the fitness of the recipient and in this respect differs from an allomone (which is the opposite: it benefits the producer and harms the receiver) and a synomone (which benefits both parties). The term is mostly used in the field of entomology (the study of insects). Two main ecological cues are provided by kairomones; they generally either indicate a food source for the receiver, or the presence of a predator, the latter of which is less common or at least less studied.