The equilibrium dynamics of native and introduced blowflies is
modelled using a density-dependent model of population growth
that takes into account important features of the life-history
in these flies. A theoretical analysis indicates that the
product of maximum fecundity and survival is the primary
determinant of the dynamics. Cochliomyia macellaria, a
blowfly native to the Americas and the introduced Chrysomya
megacephala and Chrysomya putoria, differ in their
dynamics in that the first species shows a damping oscillatory
behavior leading to a one-point equilibrium, whereas in the
last two species population numbers show a two-point limit
cycle. Simulations showed that variation in fecundity has a
marked effect on the dynamics and indicates the possibility of
transitions from one-point equilibrium to bounded oscillations
and aperiodic behavior. Variation in survival has much less
influence on the dynamics.
