Aqueous suspensions produced by grinding leaf tissue of tansy, sage, basil, catnip, dill, and rue in water deterred feeding of adult and larval Colorado potato beetles,Leptinotarsa decemlineata(Say), when tested on eggplant leaf disks in laboratory choice tests. Tansy showed the most potent antifeedant effect. Adult beetles refused to feed on leaf disks dipped in a 10% (2 g in 20 ml) suspension of tansy tissue, even after 22 h in either a choice or no-choice situation. Beetles kept for 22 h on leaf disks treated with a 1% (0.2 g in 20 ml) tansy suspension subsequently rejected the treatment to the same extent as naive beetles. Tansy treatments caused substantial mortality to beetle larvae that fed on them from egg hatching. These effects could have been caused by starvation or physiological toxicity. Tansy and other herbs show potential for use in integrated pest management programs aimed at the Colorado potato beetle.