The rates of spatial expansion of range following the introduction of
animals to new areas are extremely variable between species. Data on a
selection of species from a range of taxa show that these rates vary
over about five orders of magnitude. The range expansion of a limited
number of pest species of aphids have been mapped following colonisati
on. Studies on rates of colonisation are important as they are central
to pest risk analysis. In addition, the observed variation in rates h
ave significant implications for the development of realistic models o
f metapopulations.