Abstract
This paper is concerned with the classical Nicholson-Bailey model [15] defined by f <sub>λ</sub> (x,y) = (y(1 - e <sup>-x</sup> ), λye <sup>-x</sup> ). We show that for λ = 1 a heteroclinic foliation exists and for λ > 1 global strict oscillations take place. The important phenomenon of delay of stability loss is established for a general class of discrete dynamical systems, and it is applied to the study of nonexistence of periodic orbits for the Nicholson-Bailey model.