This paper describes a simulation model of the long-distance migration
of the moths Helicoverpa punctigera and H. armigera. The model is a c
omponent of a wide-area simulation model of Helicoverpa spp. populatio
n dynamics in inland and eastern Australia. The wide-area Helicoverpa
model will form the basis of a proposed system for forecasting migrati
ons of moths from the inland to the summer cropping areas of the east,
where they cause significant economic damage. The migration model was
implemented using the object-oriented class library of the generic mo
del GenSIM. The flexibility of the migration model was maximised by sp
ecifying simple, standard interfaces for its submodels, enabling the r
eady substitution of one submodel for another. Since this paper was pr
esented, the role of GenSIM has shifted away from providing a shell fo
r the development of aggregate models. It now focuses on the less ambi
tious task of implementing models which fit well into such aggregate m
odels. In particular, it supports the linking of models to geographic
information systems, such as that which now provides the shell for the
wide-area Helicoverpa model.