Electronic Journal of Differential Equations, Vol. 2013 (2013), No. 09, pp. 1-16. Title: Stability and Hopf bifurcation in a symmetric Lotka-Volterra predator-prey system with delays Authors: Jing Xia (Peking Univ., Beijing, China) Zhixian Yu (Univ. of Shanghai for Science and Tech, China) Rong Yuan (Beijing Normal Univ., Beijing, China) Abstract: This article concerns a symmetrical Lotka-Volterra predator-prey system with delays. By analyzing the associated characteristic equation of the original system at the positive equilibrium and choosing the delay as the bifurcation parameter, the local stability and Hopf bifurcation of the system are investigated. Using the normal form theory, we also establish the direction and stability of the Hopf bifurcation. Numerical simulations suggest an existence of Hopf bifurcation near a critical value of time delay. Submitted September 28, 2012. Published January 09, 2013. Math Subject Classifications: 34K18, 37G05, 37G10, 92D25. Key Words: Predator-prey system; delay; stability; Hopf bifurcation; normal form.