In a recent study, 3-"trans"-caffeoyl-muco-quinic acid was found to be the substance that compelled spicebush swallowtails to lay their eggs on members of Lauraceae. However, 3-"trans"-caffeoyl-muco-quinic acid is a component of the extract from sassafras plants but not from spicebush, redbay or camphor tree, the other top three host plants of spicebush swallowtails. This substance is not necessarily itself the stimulant but instead activates another as yet unknown compound that thus compels the spicebush swallowtail to lay eggs. Thus, this substance may hold the link for why some spicebush swallowtails prefer to lay eggs on sassafras rather than spicebush. In addition, 3-"trans"-caffeoyl-muco-quinic acid is a member of a family of acids, hydroxycinnamic acids, which are present in oviposition stimulants for some members of all five families of swallowtail butterflies. Hydroxycinnamic acids are also present in the extracts from host plants for two other species within the genus "Papilio": the black swallowtail butterfly, "P. polyxenes", and "P. protenor". Thus, hydroxycinnamic acids may help explain why many types of swallowtails choose to oviposit on the plants that they choose.