Simple Summary: We identified the notch gene in the reproductive system of the Basilepta melanopus beetle, a pest affecting oil tea plants. It was discovered that the Notch signaling pathway is crucial for the early development of insect ovaries. Specifically, suppressing the Notch gene expression by RNAi led to impaired ovarian development, decreased mating rates, and reduced egg production. These findings highlight the potential of RNAi-based, Notch-targeted pest control strategies as a practical approach for managing the forest pest B. melanopus populations. Basilepta melanopus is a pest that severely affects oil tea plants, and the Notch signaling pathway plays a significant role in the early development of insect ovaries. In this study, we explored the function of the notch gene within the Notch signaling pathway in the reproductive system of B. melanopus. The functional domains and expression patterns of Bmnotch were analyzed. Bmnotch contains 45 epidermal growth factor-like (EGF-like) domains, one negative regulatory region, one NODP domain and one repeat-containing domain superfamily. The qPCR reveals heightened expression in early developmental stages and specific tissues like the head and ovaries. The RNA interference (RNAi)-based suppression of notch decreased its expression by 52.1%, exhibiting heightened sensitivity to dsNotch at lower concentrations. Phenotypic and mating experiments have demonstrated that dsNotch significantly impairs ovarian development, leading to reduced mating frequencies and egg production. This decline underscores the Notch pathway's crucial role in fecundity. The findings advocate for RNAi-based, Notch-targeted pest control as an effective and sustainable strategy for managing B. melanopus populations, signifying a significant advancement in forest pest control endeavors. [ABSTRACT FROM AUTHOR]