A hypothesis about new form of species inter-relations is advanced, basing on long term field experiments. This form of active and precise adjust of population number of subdominant species from the direction of dominants, is named “interspecies social control” and based on a balance between competition and cooperation. In this case, cooperation is a result of reciprocal parasitism. On the one hand, dominant species maintain subdominants’ density at a certain level which allows avoiding conflicts and depletion of resources and, at the same time, using them as “scouts” when searching for food and thus increasing effectiveness of hunting. On the other hand, the subdominant species steal honeydew from aphids’ populations tended by the dominants. These sophisticated inter-relations are based on interspecies communication.
