Abstract The occurrence of Dirofilaria roemeri in definitive and intermediate hosts in two separate areas in southeast Queensland, is compared. The presence of D. roemeri in a macropod species in a defined region is determined by both the geographic distribution and the biting behaviour of those species of tabanid fly which are capable of acting as intermediate host. The seasonal succession and seasonal abundance of 4 tabanid species at Durakai and 8 tabanid species at Allan are responsible for a seasonal pattern of transmission of this filarioid. Moderate to low levels of transmission occur from November through March. Maximum transmission occurs in April associated with the peak in population of Dasybasis hebes, the most important tabanid involved in transmission of D. roemeri in both areas. Findings indicate that the wallaroo is the source of infection for tabanid flies and acts as the reservoir of infection for grey kangaroos and red-necked wallabies, in southeast Queensland. Transmission of D. roemeri is discussed in the light of behavioural interactions between definitive and intermediate hosts.