All active instars of an unnamed species of Platyseiinae Evans, 1957 (Acari; Mesostigmata; Blattiscociidae) consumed freshly killed mosquito larvae in microcosms on a daily basis from February 5 - March 15. Early instar larval mosquitos were sometimes captured, killed and consumed by the mites. Other prey included crustaceans and nematodes. The mite could be placed in Platyseius Berlese, 1916, but has a broadly fused ventrianal and dorsal sheild. Aspects of the mite's taxonomy and biology, is presented in videos, illustrations and photos. Highlighted are the water-surface habits of the mite; its agility and the presence of a dorsal detritus mass. Mites used the short, sharp setae of the J, Z, S, R and JV series as a fork to lift detritus which was then moved forward onto the mite's dorsum with the 4th pair of legs. Mating rituals, social interactions and egg-laying were observed. The mite was collected in the Thistledown fresh-water springs Christchurch.