The invention comprises thiophosphoric esters of the formula <FORM:0781471/IV (a)/1> where R1 and R2 are C1-C4 alkyl, R3 and R4 are C1-C4 alkyl or together with the N atom form a saturated heterocyclic ring, alk is an ethylene residue which may be substituted and Y1 and Y2 are O or S at least one being S; water-soluble salts are included. These are made by reacting <FORM:0781471/IV (a)/2> with <FORM:0781471/IV (a)/3> where one X is halogen and the other is the Y2 cation. When the reactants are a phosphoric or thiophosphoric diester halide and an aminoalcoholate there is preferably used benzene, toluene or an excess of Y2OH as solvent. When the latter reactant is a haloalkylamine the solvent is preferably water, acetone or benzene. Examples show the preparation of the following compounds: (1) R1 = R2 = R3 = R4 = ethyl, Y1 = S, Y2 = O, alk=ethylene; (2) R1 = R2 ethyl, R3 = R4 = methyl, Y1 = S, T2=O, alk ethylene; (3) R1=R2=ethyl, NR3R4 = morpholino, Y1=S, Y2=O, alk=ethylene; (4) R1= R2=ethyl, NR3R4=morpholino, Y1=S, Y2 O, alk=propylene; (5) R1=R2=ethyl, NR3R4=morpholino, Y1=O, Y2=S, alk= ethylene, and its hydrochloride, sulphate, acetate and methanesulphonate; (6) R1=R2= ethyl, NR3R4=morpholino, Y1=Y2=S, alk= ethylene, and its hydrochloride and methanesulphonate; (7) R1=R2=R3=R4=ethyl, Y1\t =O, Y2=S, alk=ethylene; (8) R1=R2=ethyl, R3=R4=isopropyl, Y1=S, Y2=O, alk=ethylene; (9) R1=R2=methyl, NR3R4=morpholino, Y1=Y2=S, alk=ethylene, and hydrochloride and methanesulphonate; (10)R1=R2= methyl, NR3R4=morpholino, Y1=O, Y2=S, alk=ethylene, and hydrochloride; (11) R1= R2=methyl, NR3R4=morpholino, Y1=S, Y2=O, alk=ethylene and hydrochloride; (12) R1= R2=ethyl, NR3R4=morpholino, Y1=S, Y2 O, alk=isopropoxypropylene; (13) R1=R2= ethyl, NR3R4=morpholino, Y1=S, Y2=O, alk=methoxypropylene; (14) R1=R2=ethyl, NR3R4=morpholino, Y1=Y2=S, alk=methoxypropylene, and hydrochloride; (15) R1= R2=methyl, NR3R4=morpholino, Y1=Y2= S, alk=methoxypropylene, and hydrochloride; (16) R1=R2=ethyl, NR3R4=morpholino, Y1=Y2=S, alk=ethoxypropylene; (17) R1=R2= ethyl, R3=R4=methyl, Y1=S, Y2=O, alk= methoxypropylene, and its hydrochloride. The following tertiary amino alcohols are made from the appropriate secondary amines and glycidol ethers: 1-alkoxy-3-morpholino-propan-2-ols, where the alkyl group is methyl, ethyl or isopropyl, and 1-methoxy-3-dimethylamino-propan-2-ol. 2 - Chloro - 1 - methoxy - 3 - morpholino - propane and 2 - chloro - 1 - ethoxy - 3 - morpholinopropane are prepared from the corresponding alcohols and thionyl chloride. Reference has been directed by the Comptroller to Specifications 738,839 and 740,563.ALSO:Insecticidal compositions contain as essential ingredient a basic thiophosphoric ester of the formula <FORM:0781471/VI/1> (or salt thereof) where R1 and R2 are C1 -C4 alkyl, R3 and R4 are C1-C4 alkyl or together with the N atom form a saturated hererocyclic ring, alk is an ethylene residue which may be substituted and Y1 and Y2 are O or S, at least one being S. The esters are active as contact and systemic insecticides when applied to plants from aqueous solutions or emulsions. They may be emulsified with the aid of polyglycol ethers or thioethers, together with liquids such as alcohols or hydrocarbons, or solids such as talcum, kaolin, kieselguhr or bentonite. The esters may also be used in the solid form with the above carriers and also adhesive and wetting agents if desired. Examples of suitable compositions are (1) aqueous solutions of O:O - diethyl - S - (b - morpholino - ethyl) monothiophosphate and its hydrochloride, sulphate, acetate and methanesulphonate, O:O-diethyl - O - (b - diethylaminoethyl) monothiophosphate, O:O - diethyl - S - (b - morpholinoethyl) dithiophosphate methanesulphonate, O:O - dimethyl - O - (b - morpholino - ethyl) monothiophosphate hydrochloride and O:O-dimethyl - S - (b - morpholino - ethyl) dithiophosphate hydrochloride; (2) aqueous dispersions of O:O-diethyl-O-(b -morpholino-ethyl) monothiophosphate and O:O - diethyl - S-(b - morpholino - ethyl) dithiophosphate, using p - iso - octylphenyl octaglycol ether as emulsifier; and (3) a dusting agent comprising O:O - diethyl - O - (b - dimethylamino - ethyl) monothiophosphate and talcum. Other suitable esters are mentioned. Reference has been directed by the Comptroller to Specifications 738,839, [Group IV (b)], and 740,563.