Two calanoid copepod genera, Boeckella and Calamoecia have broadly similar geographic distributions in Australia but Boeckella is more common than Calamoecia. A field survey and literature search indicate that Boeckella is usually the first calanoid to colonize newly formed bodies of water, and Boeckella is more common in temporary pools and in high altitude environments. Boeckella usually produces larger clutches than Calamoecia, increasing its probability of establishment in lakes and ponds; calculations indicate that Boeckella's probability of establishment is far greater than that of Calamoecia. That Calamoecia is common on the North Island of New Zealand may be due to the presence of planktivorous fish; small species are more likely to survive in such environments. Calamoecia clutches may be able to move more often and farther than those of Boeckella but Calamoecia remains rare because its probability of establishment is low. Boeckella may be able to survive temporary pool environments not only because it can produce larger clutches, but also because many species in this genus are highly pigmented, and as such can survive brightly lighted environments. Patterns of abundance of North American diaptomids appear to be consistent with factors affecting those of Australian and New Zealand centropagids.