Disclosed are selected O-(2-trichloromethyl-4-pyrimidinyl)-O,O-dialkyl phosphorothionates and O-(2-trichloromethyl-4-pyrimidinyl)-O,O-dialkyl phosphoronates having the formula: ##STR1## wherein Y is an atom selected from the group consisting of sulfur and oxygen; R is a lower alkyl group having 1 to 4 carbon atoms; R.sup.1 is hydrogen, a lower alkyl group having 1 to 4 carbon atoms, halo or nitro; and R.sup.2 is a lower alkyl group having 1 to 4 carbon atoms or an amino group. These compounds have been found to exhibit insecticidal activity.