Occurrence of Trombiculid Mites on Arthropods

Abstract

MITES of the family Trombiculidæ include the European harvest-mites and many other notorious scrub-itch mites, as well as the vector of scrub typhus. A closely related group, the Leeuwenhoekiidæ, has also been given familial status¹, both these families having been split off from the Trombidiidæ. Trombidiid and leeuwenhoekiid adults are superficially alike; but adult trombiculids are easily distinguished by being constricted to a figure of eight. The nymphal and adult stages of all three groups are non-parasitic, so far as is known; but the larvæ collectively appear to be the most numerous of all acarine ectoparasites in the tropics. Larval trombidiids are common parasites of insects, while leeuwenhoekiid larvæ have been found parasitizing mammals, birds, reptiles, amphibia, and, more recently, arthropods². That the trombiculid larvæ (‘chiggers’) parasitize only vertebrate hosts is, however, generally accepted as part of the definition of that family³. The following records of three species of trombiculids parasitizing arthropods in Malaya are therefore of considerable interest, and it is hoped that this note may stimulate more attention to this unexpected source.