Problems that are often encountered in increasing the production of large chili plants are pests and diseases. Some important pests that generally attack chili plants are armyworms, aphids, fruit flies, and mites. The study aimed to obtain citronella biopesticides that were effective in controlling fruit fly pests on large chili plants, using a randomized block design (RBD) with 5 levels of treatment and 5 repetitions. Biopesticide treatment consisted of citronella ash biopesticide (Ts4), citronella extract (Ts3), citronella oil (Ts2), existing (Ts1), and without biopesticide (Ts0). The results showed that citronella oil biopesticides (Ts2) had better potency than other biopesticides and controls. All citronella biopesticide treatments have low effectiveness against fruit fly pests (<40%). The main weather factor is high-intensity rain which greatly affects the effectiveness of biopesticide in the process of controlling fruit flies. Economically, the application of citronella biopesticides technology and existing biopesticides is beneficial for businesses. The value of income per hectare from large chili farming starts from the highest to the lowest respectively: treatment Ts2 (income Rp. 60,977,000 with a B/C ratio = 2.640), Ts3 (income Rp. 57,852,000 with a B/C ratio = 2.516), Ts1 (income Rp. 57,527,000 with a B/C ratio = 2.504), Ts4 (income Rp. 53,952,000 with a B/C ratio = 2.346) and Ts0 (income Rp. 46,852,000 with a B/C ratio = 2.171). With an average B/C ratio of > 1, it means that the citronella biopesticide technology is feasible to be developed to control fruit fly pests on large chili plants.