Modeling interactions of hemlock woolly adelgid and two biological control predatory beetle species in the Great Smoky Mountains National Park

•Novel model represents population dynamics of A. tsugae and two biocontrol organisms.•Systems of ordinary differential equations form our life stage structured model.•Model seasonality reflects active life stages and demographic mechanisms.•If one or both predators are absent, A. tsugae densities are higher over time.•Model structure illustrates plausible mechanisms for predator coexistence.