The two-stage contact process

We introduce a multitype interacting particle system, which is a natural ge neralization of the contact process. Here, individuals in the population ha ve two life stages, young and adult. Only adults can give birth and each ne w offspring is young. Transition from young to adult occurs at constant rat e, and individuals die at rates that depend on their life stage. Important to the analysis of this process is the construction of a multitype dual pro cess.