Pesticide application is used in horticulture to reduce plant damage from organisms such as insects and mites. Systemic insecticides are highly ef fi cacious and readily taken up by plant tissues. However, pesticide -treated plants may impose risks to nontarget insects or other organisms within ecosystems. In this study, insecticide residues in nectar, leaves, and fl ower petals of the horticulturally signi fi cant herbaceous annual snapdragon, Antirrhinum majus (Lamiales: Plantaginaceae), were assessed at two locations over several weeks following foliar and drench treatment with fi ve systemic insecticides. Concentrations of the insecticides were determined by liquid chromatography - mass spectrometry. The independent effects Application Method , Application Rate , and Time were statistically signi fi cant among all active ingredients in the three matrices in both sites in California (CA) and New Jersey (NJ). The interaction effects were also generally statistically signi fi cant in the CA site but less consistently so in the NJ site, dependent on the active ingredient and matrix. Post hoc analyses found the highest residue concentrations in leaves and the lowest in nectar, a trend generally consistent over time regardless of active ingredient for both the CA and NJ sites. The results of this study are discussed in the context of conserving pollinators and other bene fi cial insects. It is recommended that similar studies should be implemented in different geographical regions and climates, along with multiyear studies for perennial ornamental plants.