The distribution and biology of the harvest mite in Great Britain (Trombiculidae, Acarina)

Abstract

Previous work is discussed and described. The numbers of larvae present in a square yard of soil can be estimated by the use of caged guinea-pigs or by light traps. The infestation observed on the ears of wild rabbits gives a rough index of the population present in a given area.Using a modified light trap, gorged larvae can be collected from their hosts.Adults can be extracted from light, friable soils by flotation in water and from any type of soil by the Salt-Hollick soil-sampling machine.The harvest mite occurs throughout the British Isles. It seems possible that climate and the geological origin of the soil do not affect harvest mite abundance. They are, however, less numerous on heavy clays.Larvae are most abundant in late summer and autumn. Adults remain constant in numbers throughout the year.The larvae appear to infest most warm-blooded vertebrates. They do not attack at night. Nymphs have been observed sucking the contents of nymphophanes.Adults have been found at a depth of 3 ft. They appear to come nearer the surface in warm, moist weather, but are driven down by drought, heavy rain and ground frost.