Tujuan dari penelitian ini adalah untuk mengetahui efektivitas dan konsentrasi yang tepat dari Metarhizium spp. dan ekstrak serai terhadap mortalitas wereng hijau. Penelitian dilaksanakan di greenhouse BRMP (Badan Perakitan dan Modernisasi Pertanian) Aneka Umbi, Lanrang, Kabupaten Sidenreng Rappang pada bulan April-Juli 2025. Penelitian ini menggunakan Rancangan Acak Lengkap dengan 5 perlakuan, terdiri dari P0: Aquades, P1: 10 gr Metarhizium spp./100 ml air, P2: 12,5 gr Metarhizium spp./100 ml air, P3: 100 ml ekstrak serai/1000 ml air dan P4: 125 ml ekstrak serai/1000 ml air, diulang sebanyak 3 kali sehingga diperoleh total 15 unit percobaan yang terdiri 4 sampel masing-masing unit percobaan, sehingga terdapat 60 unit pengamatan. Hasil penelitian menunjukkan perlakuan 12,5 gr Metarhizium spp./100 ml air memberikan pengaruh yang sangat nyata terhadap wereng hijau dengan mortalitas 100%, LT50 36 jam dan mematikan wereng hijau pada 2 HSA. The purpose of this study was to determine the effectiveness and appropriate concentration of Metarhizium spp. and lemongrass extract on green leafhopper mortality. The research was conducted in the greenhouse of BRMP (Badan Perakitan dan Modernisasi Pertanian) Aneka Umbi, Lanrang, Sidenreng Rappang Regency, from April to July 2025. This study used a Completely Randomized Design with 5 treatments, consisting of P0: Aquades, P1: 10 g Metarhizium spp./100 ml water, P2: 12.5 g Metarhizium spp./100 ml water, P3: 100 ml lemongrass extract/1000 ml water and P4: 125 ml lemongrass extract/1000 ml water, repeated 3 times so that a total of 15 experimental units were obtained consisting of 4 samples for each experimental unit, so there were 60 observation units. The results of the study showed that the treatment of 12.5 g Metarhizium spp./100 ml water had a very significant effect on green leafhoppers with 100% mortality, LT50 36 hours, and killed green leafhoppers at 2 DAA.