Abstract: An agricultural or horticultural miticidal composition for controlling mites which cause damage to plants, said miticidal composition comprising(1) a liquid carrier and/or a solid carrier, and(2) as an active ingredient, a trialkyltin compound of the formula ##STR1## wherein R.sup.1 represents a linear alkyl group having 6 to 11 carbon atoms, R.sup.2 represents a hydrogen atom or a methyl group, the total number of carbon atoms of R.sup.1 and R.sup.2 is from 7 to 11, m is an integer of 1 or 2, and X represents a chlorine atom, a bromine atom, a fluorine atom, a hydroxyl group, an acyloxy group, a dithiocarbamate group or a group of the formula --SR.sup.3, in which R.sup.3 represents an alkyl group having 1 to 12 carbon atoms or an aryl group, when m is 1, and a member selected from the class consisting of an oxygen atom, a sulfur atom and a sulfuric acid group when m is 2; and a method for controlling mites using the same.