A pesticidal composition comprises, as the sole pesticidally active component, a storage-stable aerated gel composition comprising 30 to 97% by weight of water, 0.2 to 5% by weight of a gelling agent selected from xanthan gum, sodium alginate and neutralized carboxyvinyl polymer and 2 to 5% by weight of fine particulate, hydrophobic silicone-treated silica having a surface area of from 80 to 300 m²/g. The composition is in the form of fine particles of an aqueous gel containing the water and gelling agent, the surfaces of which fine particles are coated with a coating of the finely particulate hydrophobic silica. The composition is useful in a method of controlling pests, particularly insects and acarids.