An aqueous carrier/ agent delivery solutions containing both iron and phosphate in a water-soluble and their use in pesticidal compositions with a carrier material edible to pests wherein the pesticidal composition is effective to kill pests upon ingestion. The present invention relates specifically but not exclusively to water soluble iron and phosphate compositions where inorganic phosphate are the principal chelating/ligand agent responsible for retaining iron solubility thus negating the need to have an organic chelating agent present in the composition for efficacy.
