Biology Department, Faculty of Mathematics and Natural Sciences, State University of Semarang, Semarang, Indonesia.

Email: nikensubekti@mail.unnes.ac.id

Weaver ants (Oecophylla smaragdina) are insects belonging to the order Hymenoptera. Fipronil and imidacloprid are chemicals used to kill ants. The purpose of this study was to analyze comparison the effectiveness of the fipronil and imidacloprid active substances to control weaver ants. The methods used in this study include the preparation of test insects, making of toxic bait, test the effectiveness of toxic baits, calculation of mortality and data analysis. The data were analyzed statistically using One Way ANOVA test and probit analysis. ANOVA test results indicates that there is a significant difference in the percentage of mortality between the treatment groups. In addition, the lowest LT₅₀ and LT₉₀ ​​occurred in the use of bait with a combination of the active substance fipronil, namely LT₅₀= 6.31 hours and LT₉₀ = 11.21 hours. The active substance fipronil only takes 12 hours to cause weaver ants to experience 100% mortality. In the group of weaver ants who were given bait with a combination of the active substance imidacloprid, the ants died 100% after 24 hours of treatment. The results of this study show that the active substance fipronil is more effective in controlling weaver ants compared to the active substance imidacloprid.