Telephone!
There are three major methods of communication: Audible (singing of crickets, cicadas etc.) Visual (wing waving in Tephritid flies, warning colouration of toxic insects, honeybee waggle-dances etc.) and Olfactory (pheremones and the like).
Although we humans are aware of the first two, the third is probably the most important to insects-the reason for the feathery antennae of many species (such as moths) is to better pick up the scent of the female, ants and bees are 'controlled' by the queen using pheremones-and communicate amongst themselves too (when a bee stings it also lets off a pheremone that says 'attack here' to other bees for example), there are many other examples too.