A new coumarin, 6,7-dimethoxycoumarin (scoparone) was found in ammonia stressed Pima cotton stems along with 6-methoxy-7-hydroxy-coumarin (scopletin) which has been found in cotton bracts by Wakelyn et al. (1974). These coumarins were isolated and crystallized; their identities were established by proton, (13)C and mass spectroscopy. The biological activity on Heliothis zea and Pectinophora gossypiella will be described.