New thienylmethyl-thiophosphoric acid esters of the formula ##STR1## where R.sup.1 denotes methyl or ethyl, R.sup.2 denotes linear or branched alkyl of a maximum of 5 carbon atoms, X denotes oxygen or sulfur, Y denotes sulfur or --NH--, Z denotes halogen, and n denotes one of the integers 0, 1, 2 and 3, which are effective against pests, especially insects, Arachnida and Nemathelminthes, and pesticides containing these compounds as active ingredients.