Pyrazoline derivatives having the formula ##STR1## wherein R.sup.1 represents hydrogen atom, a lower alkyl group, phenyl group or a halogen-substituted phenyl group; R.sup.2 represents hydrogen atom or phenyl group which can have halogen substituents; X represents oxygen or sulfur atom; Y and Z respectively represent hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, nitro-group, trifluoromethyl group, a lower alkylthio group, an acyl group, nitrile group or a lower alkyl sulfonyl group.