Figure 6. Relationship between xm, the log-suitability of the marginal plant as determined by simulation, and μ/b, the mean survivorship barely sufficient to support the herbivore population at equilibrium.  As predicted by equation (22), xm is about 2 log units greater than μ/b for the random foraging simulation, but this difference declines as herbivore preference (A) increases (equation 25).  xm for the “perfect forager” is less than μ/b.  This results from the ability of such foragers to successfully exploit the production of “defoliated” plants and are not dependent on the marginal plants for the production of new adults.