We obtain conditions under which every positive solution of a difference eq
uation of the form y(n+1) = y(n-1)f(y(n-1),y(n)), n = 0, 1,2,... is attract
ed to its positive equilibrium. We also obtain conditions under which every
positive solution approaches a two-cycle, which may be an equilibrium.
The results apply to a population model with two age classes.