The ecological basis for modelling the off-host phase of the Boophilus annulatus (Say) (Acari: Ixodidae) life cycle is examined with respect to microenvironments of three predominant vegetation communities in the Tamaulipan biotic province. Thermal summation and biophysical modelling approaches are contrasted for modelling embryonic development and eclosion. Applications of models to surveillance, eradication and quarantine epidemiology are discussed. Models integrated with aerial infrared photography through a Geographic Information System (GIS) enable spatial heterogeneity of rangeland vegetation communities to be characterized and analyzed across quarantine levels.