Abstract: Compositions containing insect behavior modifying compounds containing carbon-to-carbon unsaturation, e.g. pheromones, are stabilized by the addition of a tertiary phenylene diamine of formula: ##STR1## wherein R.sup.1 represents an aromatic residue, R.sup.2 represents H or an alkyl, alkenyl, cycloalkyl, cycloalkylalkyl, alkaryl, aralkyl, aryl, acyl, acyloxy or nitroso group and R.sup.3 and R.sup.4, which may be the same or different, each represents an alkyl, alkenyl, cycloalkyl, cycloalkylalkyl, alkaryl, aralkyl, aryl, acyl, acyloxy or nitroso group.These compositions are usefully enclosed in micro-capsules for spraying in an area of insect infestation in order to disrupt mating patterns, and the invention particularly applies to micro-encapsulation of the compositions in polyureas, the tertiary phenylene diamines having the advantage that they do not react with the diisocyanate monomer during the micro-encapsulation process.