Mites on stalks

Mites on stalks

Observation - Mites on stalks. Description: For years these 'mites on stalks' have appeared on insects that I've found, usually in herbivore dung, though also in compost. They're about 1 mm long, very tough, and attached to the integument of the insect by a very strong thread. Common hosts are beet

For years these 'mites on stalks' have appeared on insects that I've found, usually in herbivore dung, though also in compost. They're about 1 mm long, very tough, and attached to the integument of the insect by a very strong thread. Common hosts are beetles such as Aphodius, Geotrupes, Hister though in the one shown it is on Tachinus subterraneus from my compost heap in Hampshire, April 2013.
Can anyone enlighten me? What are they? What is the relationship with the insect and the purpose of being attached thereto? Curiosity has got the better of me!