Fatty alcohol ethoxylates of the formula CH3-(CH2)m-CH2-(-O-CH2-CH2-)n-OH (I) in which m represents average values from 8.0 to 13.0 and n represents average values from 6.0 to 17.0 are highly suitable for use as penetrants for insecticidally active compounds from the group of the neonicotinyls when employed in amounts such that they are present in the commercial formulations in concentrations from 0.1 to 30% by weight and the weight ratio of neonicotinyl to fatty alcohol ethoxylate is from 1:0.1 to 1:2.0.