red mite predators

As title. Obviously cannot be used in combination with usual measures but interesting. They are subject of an article in British hen welfare trust newsletters which many of you will read anyway, but if not here is the link:
http://www.netmailing.co.uk/ebooks/bhwt/2012/issue-2/newsletter/index.html

Quote I dont understand how they suddenly stop eating the redmites and wait for their numbers to build up again.
unquote

It's badly written. With any predator prey relationship the balance is dynamic. Prey increases so predator numbers follow just because food is available. When prey reduces then some predators starve and lower numbers are to be found. The cycle repeats. Here it means that red mite must exist and multiply to provide food BEFORE the predator numbers start to increase. Probably not what we would want in our chook houses.
I certainly agree about the risks of deliberately introducing  species, especially predators - just look at Cane toads in Australia - which emphasises that it is always a good idea to watch what others are doing. Today's commercial hen house saviour (organic, ecologically sound etc, etc) could be our problem in the not too far distant future.