“…They studied the ultimate boundedness in the mean of a solution and estimated the sample Lyapunov exponent of the solution. The modified model for Nicholson's blowflies was described by Zhu et al 2 as follows: with initial conditions , for s ∈ [− τ , 0], ϕ ∈ C ([− τ , 0], [0, + ∞ )), ϕ (0) > 0. X ( t ) denotes the total number of Nicholson's blowflies at time t , δ represents the daily mortality rate of adult Nicholson's blowflies, p is the maximum daily spawning rate, τ is time of each generation, gives the maximum growth rate of reproduction of Lucilia cuprina, σ 2 is the white noise intensity.…”