Cultivation of tropical flowers has expanded considerably in Brazil, justifying efforts to determine the arthropods associated with it. Heliconia species are some of the most important tropical flowers in Brazil. Mites of the families Ascidae, Blattisociidae and Melicharidae are commonly found on those plants. They disperse from flower to flower on hummingbirds. The objective of this study was to identify the diversity of mites of this group in tropical flowers, with emphasis on Heliconia species, in Brazil and to determine the fluctuation of the population of these mites in Piracicaba, Sao Paulo state. Specimens from Amazonas, Bahia, Pernambuco, Minas Gerais, Rio de Janeiro, Santa Catarina and São Paulo States were examined. Mites of the genera Asca and Iphidozercon (Ascidae), Cheiroseius and Lasioseius (Blattisociidae), and Proctolaelaps and Tropicoseius (Melicharidae) were collected in flowers of four plant families, with Lasioseius being the most diverse genus. Overall, most specimens found belonged to Tropicoseius, especially Tropicoseius venezuelensis Baker & Yunker; this was the dominant species on five of 13 Heliconia species/hybrids considered in this study. Samples of panicles of Heliconia rostrata Ruiz & Pavón were collected every 2 weeks, in Piracicaba. Six species of those mite families were found, among which Tropicoseius heliconiae Baker & Yunker and T. venezuelensis were the most numerous. The highest population levels of mites of those three families occurred at the beginning and at the end of the year, coinciding with the highest levels of rainfall, relative humidity and temperature, when plant flowers were most numerous and vigorous. Along each panicle, the highest mite densities were found in inflorescences of the three distal eighths of the panicles, where nectar and pollen were probably most abundant.