Have you ever noticed little red dots scattered around on the bodies of various arthropods? These are 8-legged mites (Arachnids). Most do no harm to their "taxi driver", they are just hitch-hiking a ride from place to place. Yet there are some mites that are true parasites.
Let's take the whole family for a Sunday cruise. Harvestmen (Daddy-Longlegs) are voracious predators, and the mites probably don't mind the scraps. But there is one genus, Leptus, whose larvae do parasitize Harvestmen on their femurs, and that 'might' be what's happening here.
"I'm in the mood for Possum Pate". Well you just might get your wish. Carrion beetles, also known as Burying Beetles, are well known as the vultures of the insect world. They tear apart road kill and make it available to the young beetles. A rare example of parental care in insects.
The beetles provide the transportation to the carrion. The mites prey upon fly pupa and maggots, thus reducing the competition for the beetles. Mutualism at it's best. One mite species does the same to honeybees, and a few years ago may have been responsible for as much as one-third of the honeybee population crashing.