Cestodes of the family Anoplocephalidae Cholodkovsky, 1902, in their adult form, parasitize a variety of hosts, including reptiles, birds and mammals. To complete their life cycle, an intermediate host is required. This study gives a critical review of the life cycles of genera principally important to veterinary medicine (but sporadically infecting man): Anoplocephalinae (Anoplocephala, Anoplocephaloides, Bertiella and Monieziu) and Thysanosomatinae (Avitellina, Stilesia, Thysaniezia and Thysu-nosomu), using data reported by others and our own observations. The accepted paradigm on the biology of the anoplocephalid cestodes is that oribatid mites (Acarina) serve as intermediate hosts. However, as regards the genera Avitellina, Thysaniezia and Thysanosoma, it is still unclear whether oribatid mites are indeed the intermediate hosts, as larval forms (cysticercoids) have also been found in collcmbolans and psocids. Using the controversial biological cycle of Thysanosoma actinioides (Diesing, 1834), a theoretical methodological research proposal for parasitology was constructed which attempts to define a conceptional mark enabling us to predict and explain the parasite-hosts’ related phenomenon. Aspects of this proposal are discussed using the biology of the cestodes of family Anoplocephalidae, as examples.