Insecticidal compositions comprising: a) between 0.001 and 5%, preferably between 0.05 and 0.5%, of a solid compound of 1-phenylpyrazole type, in particular 1-[2,6-Cl.sub.2 -4-CF.sub.3 -phenyl]-3-CN 4-[SO-CF.sub.3 ]-5-NH.sub.2 pyrazole; and b) between 0.05 and 10%, preferably between 0.1 and 5%, of a thickener; and c) between 5 and 50%, preferably between 10 and 40%, of propylene glycol, the compound of formula (I) being in the dissolved state in the said propylene glycol. Method for controlling insects using this composition, in particular for controlling ants.