This paper reports the development of the canid filarial worm, Dipetalonema dracunculoides, in the brown dog tick, Rhipicephalus sanguineus by determining whether development is similar within larval, nymphal and adult stages of infected ticks. This study demonstrates that only infected nymphal ticks can support the complete development of the filarial worm. Infected larval ticks are not suitable intermediate hosts, nor are infected adults. Development depends on some stage-specific property of the vector, and the maturation to the infective stage is stimulated during the course of the nymphal-adult moult.