The use of synthetic pesticides has raised concerns due to their toxic impact on the environment and human population as well. As a result, there is developing interest in exploring alternative pest control methods, such as herbal pesticides derived from natural sources. This study aimed to investigate the efficacy of a dry flower extract of Tagetes erecta as an herbal pesticide on larval mortality and emergence of Agrotis ipsilon, a common agricultural pest. The experiment involved conducting bioassays using different concentrations of the dry flower extract on Agrotis ipsilon larvae. Mortality rates were recorded at regular intervals, and observations were made on the emergence of adults from surviving larvae. Additionally, the effects of the extract on larval developmental stages were examined. The experiment were perform on infected brinjal and tomato plant to find out the impact of dry aqueous extract of Tagetes erecta (marigold) on larval mortality and the emergence of Agrotis ipsilon. Finding shows that larval mortality and emergence on brinjal towards Agrotis ipsilon (Hufn) varies with five gram (2% to 38%.),10 gram (13% to 63%.), 15 gram (21% to 68%) and 20 gram (29% to 85%.) and on tomato towards Agrotis ipsilon (Hufn) with five gram (4% to 26%), 10 gram (12% to 58%), 15gram (16% to 70%.) and 20 gram (28% to 89%). The larvae showed comparative tolerance in route of increasing age and time.