Signal variety and communication in social insects

Social insect colonies contain from tens to millions of individuals. Their social organization is based on an efficient communication sys- tem, in which multimodal signals can be distinguished. This article aims to give examples that illustrate the use of visual, acoustic, tactile, sometimes magnetic, and especially chemical signals in communica- tion among social insects. The majority of insect species live a solitary life, with few contacts between con- specific individuals. Temporary aggregations may sometimes occur because of abundantly present food (as is e.g. well known in the desert grasshoppers), or conspecific males and females meet briefly during the mating season to copulate. Social insects, however, are characterized by communities in which they live in permanent contact with their nestmates. Bees and bumblebees, wasps, ants and termites since long have fascinated man because of their well organized and often impressive colonies. Their social lifestyle goes along with the inevitable development of a communication system, that allows the individual members of the colony to exchange information. This social language can occur via various sensory channels, using visual, acoustic, tactile, sometimes magnetic, and espe- cially chemical signals. This article aims to have a closer look at this communication system in social insects, and to illustrate the various modalities that characterize it with a num- ber of examples. We first illustrate the ingenious honeybee dance as an excellent example of multimodal information exchange, and then separately deal with the various sensory channels that can play a role in social insect communication. Honeybee dancing One of the best known examples of social insect communication is represented in the recruitment system by means of dancing displays that honeybee workers