these are much more of a problem in winter,
when plants are kept dry.
rather than during the growing season when plants are (hopefully) actually watered.
so i am quite surprised as I thought the season just ended.
RSM absolutely HATE water.
mist spraying with plain water is fantastic.
high humidity does slow them down,
but its not as good as watering to the point of runoff.
top water all plants where appropriate.
they love Sulcorebutia, like rauschii.
also miniature Mamm. SP. especially the good ones like saboae etc.
and of course Loph. SP.
Gymnocalycium (particularly the small choice SP like ragonesei
I think they will go for anything if it is kept dry enough,
however some plants do indeed tend to be more prone than others,
and it seems that RSM specifically seek out the slowest/choicest/rarest specimens in a collection.
The best way to get rid of them is water, and/or a miticide.
problem is you don't want to top water that prized 15yo self rooted Lophophora eh.
The worst thing you can do is apply a systemic insecticide, mites are not insects and it can actually result in increasing the mite population by killing off their natural predators.
There are thouands of mite species, some are visible to the naked eye and are predominately natural predators of the pest ones and then there are rust mites which are like RSM.
Apparently under ideal conditions a single female RSM can spawn a population of 1mil in under a month!
(which therefore means they are possibly the most effective organisms in the world at gaining pesticide resistance. doh)
so they can never be eliminated and your miticide will be eventually be rendered useless with prolonged use, thus you will have to try other chemicals or explore other means of treatment.
also the miticide kills all mites including the predacious species which naturally keep the mites in check and I'm assuming being predacious these have a comparatively much slower population turn over rate vs. RSM so will take much longer to gain pesticide-resistance also.
Oil based contact pesticides will kill them and the mites obviously cannot gain resistance to these but the use of these requires much more care such as placing the affected plant in the shade whilst it is treated and washing the oil off later.
has anyone tried any biological controls for these?