The parsnip webworm, Depressaria pastinacella, specializes on plants containing furanocoumarins, particularly wild parsnip, Pastinaca sativa, and cow parsnip, Heracleum lanatum. Webworms detoxify these compounds with cytochrome P450s that are auto-inducible. The caterpillars also encounter a variety of other secondary compounds within these host plants. Whether other secondary compounds encountered by the caterpillars induce furanocoumarin metabolism is an open question. Previous experiments with the Eastern black swallowtail, Papilio polyxenes, another specialist on furanocoumarin-containing plants, have suggested that some non-furanocoumarin compounds will induce furanocoumarin metabolism. Inducibility of metabolism of the furanocoumarin bergapten in parsnip webworm by a range of compounds, including those that plants use to signal attack, were tested and results are reported.