Figure 9.  Quantitative graphical model for Heliconius-Passiflora interaction incorporating heterogeneity among plants in caterpillar survivorship.  The solid curve respresent the estimated biomass of P. vitifolia along the spectrum of plant suitability for survival of Heliconius pachinus caterpillars.  The hatched area represents the portion of the spectrum which produces most of the herbivores; it is 2 log units wide as indicated for a random forager.  This area is about one-tenth of the estimated total of 2000 leaves per hectare, which, using equation (29), gave an estimated population size of 7/ha.  This figure is in close agreement with independently derived field estimates (see text).