The ecological system used to exemplify these points involves plantfeeding insects called psyllids or jumping plant lice. These are small sternorrhynchan bugs that suck sap from plants to gather nutrients for their life processes. In terms of ecological study, this is an unusual case because

ã Introduction ã Outbreaks of Australian psyllids ã The demographic approach ã The autecological approach

ã Extending each of the psyllid studies ã Inferences for general ecological interpretation

it represents one of the few systems that have been investigated from both of the research traditions that are currently available to ecologists.