Species of the genus Macrocheles are common predators of nematodes, oligochaetes, and the eggs and larvae of small insects and mites in a wide range of organic substrates, such as animal dung, hay, rotting stumps, galleries of bark beetles and subcortical situations, and nests or galleries of mammals, birds, and social insects, including bees (Bombus, Apis, and Melipona). These mites commonly form phoretic associations with beetles and flies to colonize fresh substrates. Typically, only inseminated females disperse, although protonymphs and deutonymphs of the Macrocheles dimidiatus species group have also been found to be phoretic.
Among mites found on bees and/or in their nests, there are two very similar species from bumble bees (Bombus spp.): Macrocheles rotundiscutis (=M. bombophilus) from Europe and Macrocheles praedafimetorum from North America. These species have a clear preference toward bumble bee nests, although they can be found in other habitats. In nests of bumble bees, the mites often reach large population sizes, feeding on a wide range of saprophagous organisms common to dung and decaying matter, without any negative effect to the hosts. Cannibalism has also been recorded. It is interesting that dispersal does not occur on bumble bees, but on a dung-inhabiting beetle that is apparently attracted to bumble bee nests by the decaying material on the bottom of the domicile (Richards and Richards, 1977).
In contrast, species reported from hives of honey bees (Apis spp.) and other social bees are habitat generalists that can probably also use bees as transport (Chmielewski, 1991a; Grobov, 1978).
Because Macrocheles species may consume harmful microarthropods in bee nests, they can be beneficial to their hosts. Predation on the bee brood is unlikely. Macrocheles may be somewhat harmful if large numbers of mites disperse on a single adult bee. For example, a single adult bee may carry up to 30 females of M. glaber (Vitzthum, 1926). In this relatively uncommon case, the bees' movements can be hampered (Homann, 1933).