The invention relates to a method for the eradication and killing of microorganisms from among insects and worms in an aqueous system, especially for the control and eradication of the larvae. A sustained reduction or killing of the larvae is achieved by a two-step method in which insecticides and a zooplankton community are used as biological agents. The insecticides specifically kill the larvae present in the aqueous system. The biological agents, which according to the invention preferably comprise competitors for food of the above microorganisms/larvae, prevent repopulation. The combined use of insecticidal and biological treatment in aqueous systems allows an efficient and permanent eradication.
