Compositions which contain, as the active ingredients, a combination of heterocyclic compounds of the general formula (I) and organophosphorous compounds, in addition to one or more compounds having a polyethyleneglycol or polypropyleneglycol chain or an ethyleneglycol-propyleneglycol copolymeric chain, or a mixture of these compounds which results in a stabilization of the active ingredients without any adverse influences on the physical properties of the formulations.

An insecticidal composition comprising (i) a compound of the formula ##STR1## wherein A is hydrogen, alkyl or a divalent group connected to B, B is alkyl, ##STR2## or a divalent group or atom connected to A, R is hydrogen, acyl, alkyl or optionally substituted heteroarylalkyl, Y is ##STR3## T.sup.1 is hydrogen or optionally substituted alkyl, and X is an electron attractive group, and (ii) a synergistically effective amount of a methylenedioxybenzene derivative.

An imidazolidine derivative having the formula (I) or its salt: ##STR1## wherein X is an alkyl group which may be substituted, an alkenyl group which may be substituted, an alkynyl group which may be substituted, ##STR2## (in which each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is independently a hydrogen atom or an alkyl group, R.sup.5 is an alkyl group which may be substituted with a halogen atom, a cycloalkyl group which may be substituted or a phenyl group which may be substituted, W is an oxygen atom or a sulfur atom, and each of k, l, m and n is independently 0 or 1, provided that (a) case where all of k, l and m are 0 at the same time and (b) case where m and n are 0 at the same time and R.sup.5 is an alkyl group which may be substituted with a halogen atom, are excluded), or ##STR3## group (in which each of R.sup.6 and R.sup.7 is independently a hydrogen atom or an alkyl group, each of R.sup.8 and R.sup.9 is independently an alkyl gorup, R.sup.10 is an alkyl group which may be substituted, an aryl group which may be substituted, a pyridyl group which may be substituted, an alkenyl group which may be substituted with a halogen atom or an alkynyl group which may be substituted with a halogen atom); Y is a 6-chloro-3-pyridyl group or a 2-chloro-5-thiazolyl group; Z is a hydrogen atom, an alkyl group or an acyl group; and j is an integer of from 0 to 2.

Compositions which contain, as the active ingredients, a combination of heterocyclic compounds of the general formula (I) and organophosphorous compounds, in addition to an amorphous silica additive selected from the class consisting of: (a) an amorphous silica obtained by a process, wherein an amorphous silica hydrate, which has been produced by a wet synthetic, method, is either silylated or heated to effect an etherification so as to decrease the surface silanol radicals of the amorphous silica hydrate, and (b) an anhydrous, amorphous silica obtained by a dry synthetic method, or a silylated derivative thereof, and optionally one or more compounds having a polyethyleneglycol or polypropyleneglycol chain or an ethyleneglycolpropyleneglycol copolymeric chain, or a mixture of these compounds which results in a stabilization of the active ingredients without any adverse influences on the physical properties of the formulations.

The present invention relates to new macroemulsions which contain 0.001 to 60 percent by weight of at least one active compound from the class comprising the phosphates and/or carbamates, 0 to 50 percent by weight of aromatic diluents, 0.001 to 20 percent by weight of polyvinyl alcohol having a mean molecular weight of between 5,000 and 150,000 and a content of acetate groups of between 2 and 30 mol %, and/or 0.001 to 20 percent by weight of a nonlphenol/propylene oxide/ethylene oxide adduct of the formula ##STR1## in which X represents integers from 10 to 50 and Y represents integers from 15 to 65, and/or 0.001 to 20 percent by weight of ethylene oxide/propylene oxide/ethylene oxide block copolymers having a mean molecular weight of between 2,000 and 8,000 and HLB values of between 8 and 30, and water and, if appropriate, additives, and in which the oil phase is dispersed in the aqueous phase in the form of droplets having a mean particle diameter of 0.1 to 3.0 .mu.m.