Entwicklungszyklus der Calyptostomiden (Acari, Trombidiformes). In the course of a complete investigation of the mite family Calyptostomidae (Trombidiformes), the following results about life cycle and development of the species Calyptostoma velutiniis (Muller) were obtained: The three active stages of development (larva, nymph, and adult) can be found ail over the year. The numerical portions of the different stages in the total number of mites, captured at different times, do not give any indication to a synchronized development in a population. - A reduced number of animais is found in summer (July/August) and winter (January/February). The development from egg to adult takes about r year, but there seem to be individual variations of a high degree. The developinent takes place in the following way: egg (15-125 days) -> praelarva (5-30 days) ->arva (up to 7 months) -> inactive resting stage (calyptostase, 11-30 days) ->- nymph (up to 6 months) ->inactive resting stage (calyptostase, 14-31 days) -> adult (up to 21 months). The larvae can be found as parasites of adult Tipulidae and Limoniidae. Other hosts are not accepted