Methamidophos is a systemic organophosphate insecticide and acaricide used against chewing and sucking insects and spider mites on crops including pome and stone fruits, citrus, potatoes, and vegetables. It is acutely toxic to humans and wildlife and has been banned or phased out in many countries, though legacy residues and illicit use still concern regulators. Food-safety laboratories include it in pesticide multi-residue screens of fruits and vegetables, and maximum residue limits govern any produce in which it might be detected, with exceedances leading to market withdrawal. Because it is also a toxic metabolite of acephate, analysts report the two together when assessing total dietary exposure.