This is always a sign that a termite colony is on decline, close to death. Actually, mites are present in colonies of many termites, but they remain inactive for most of the time. They are not predators, but necrophages which dramatically increase their population as soon as termites start dying. But, if you improve the conditions in which the colony is held, the mites will gradually become rare again...
I agree with Jan Sobotnik concerning the presence of mites in termite colonies. To control it you can use turmeric Power either directly put near to colony or mixed with water and sprinkled it. Apart from them, the RH and temperature.