Introduction............... 2 General Remarks.............. 3 Methods of Study............. 6 Acknowledgements............. 9 Family Trombiculidae............. 11 Key to Subfamilies............. 13 Subfamily Trombiculinae Ewing........... 14 Key to Genera.............. 14 Genus Trombicula Berlese........... 15 Genus Eutrombicula Ewing.......... 96 Genus Crotiscus Ewing............ 150 Genus Schöngastia Oudemans.......... 153 Genus Neoschöngastia Ewing........... 176 Genus Euschöngastia Ewing........... 182 Genus Doloisia Oudemans........... 196 Genus Riedlinia Oudemans........... 198 Subfamily Walchiinae Ewing........... 202 Key to Genera.............. 203 Genus Walchia Ewing............ 203 Genus Schöngastieila Hirst........... 210 Genus Gahrliepia Oudemans........... 212 Genus Gateria Ewing............ 216 New Genus.............. 220 Subfamily Leeuwenhoekiinae Womersley......... 227 Key to Genera.............. 228