Abstract: Dispersion containing, in addition to water, 0.5 to 20% by weight of hydrophobic silica, 0.01 to 10% by weight of a gelling additive, or viscosity-increasing additive which, as further components, contains at least one phenol or at least one phenol derivative and/or at least one aldehyde. It is prepared by dispersing the individual components successively or together in water, in which case the individual components are deaerated before and/or during the addition or the dispersion is deaerated during the individual dispersion steps and thereafter the residual air present in the dispersion is removed by application of vacuum. The dispersion can be used as insecticide and for controlling pathogenic agents.