However, it is best to wait until breeding has finished in autumn and the devils have left. Entrances under the house can then simply be sealed. If you are not sure if all adult devils have left, make a sprung one-way cat flap. This will enable them to leave but not return. Population regulation Devil and quoll populations are mainly controlled by competition for food.
People sometimes say that devils are in 'plague proportions'.
All they are really saying is that there are more than they would prefer to see. Both devil and quoll populations naturally swell dramatically each summer when young disperse into the wild. The increase is a seasonal fluctuation, not a plague. All three species are wholly protected by law. The Parks and Wildlife Service would like reports of quoll sightings and behaviour.