A storage-stable biocidal aerated gel composition comprises from 30 to 97% by weight of water, from 0.2 to 5% by weight of a gelling agent selected from xanthan gum, sodium alginate and neutralised carboxyvinyl polymer from 2 to 5% by weight of a fine particulate, hydrophobic silicone-treated silica having a surface area of from 80 to 300 m<2>/g and from 0.004 to 20% by weight of a biocide which said composition is in the form of fine particles of an aqueous gel containing the water, gelling agent and the biocide, the surfaces of which fine particles are coated with a coating of the finely particulate hydrophobic silica. The biocidal aerated gel composition can be used to control pests using one or more appropriate biocides in the composition.