Methods for treating arthropods comprising depositing at least one drop of a liquid formulation containing at least one surfactant on a solid surface of an arthropod at a contact angle sufficient to cause rapid and enhanced knockdown (KD) of the arthropod. The contact angle comprises an angle formed between a resting drop of the liquid formulation and the solid surface on which the drop rests measured, after a period of about 80 milliseconds (ms) or more from the time that a drop of the liquid formulation is deposited on the solid surface, at a contact point between a tangent line drawn on a liquid/vapor interface surface of the resting drop in contact with the solid surface and a tangent to the solid surface on which the drop rests.
