We analyzed the population dynamics of flies in respect to ovipositional behavior and intraguild predation, using data from natural and experimental populations of exotic and native blowflies. Two hypotheses regarding the interspecific interaction dynamics of blowflies were investigated. The first hypothesis proposed that ovipositional behavior in blowflies could be influenced by the previous presence of different species on the ovipositional substrate. The second hypothesis proposed that intraguild predation, found in some blowfly species, could influence the equilibrium dynamics in blowflies. Two experiments were performed to test these hypotheses. To test the first, blowfly larvae of different species were placed in traps prior to posture by adult flies in the field. To test the second, larvae of different blowfly species were added to the diet of an intraguild larval-predator blowfly, with fecundity and survival being estimated as a function of larval densities. For the first experiment, the highest abundance of flies was found in traps where no larva had been placed, suggesting that the previous presence of different species influences ovipositional behavior. For the second experiment, intraguild predation effects were noted, showing that the larval predatory action exerts a positive influence on the population, increasing its demographic parameter values and consequently making possible the emergence of complex behaviors, such as cycles and chaos.