I am not sure quite what is going on but I have never had such a problem with spider mites as I have this year (it seems that fungus gnats are also way worse but that’s a post for another time)
This photo is of some office plants shortly before I took them to the dumpster (no compost pile at work). I am not sure quite what happened–if these plants started the infestation–as you can see, they are infested beyond saving–but last week we carted out a pothos that had been in the office forever. As I remarked, it predated me and I have worked there 12 years. So that was a real loss, but it was equally as infested as these plants. Which plant infested which, I don’t know.
I do understand why this happens so quickly at work. The office faces south and the building is brick. Every sunny day, the offices where our plants are heat naturally to very warm temperatures. So these insects, which love dry warm air, breed rapidly as they are known to do.
They have a much tougher time in my cold house, thank goodness, but I still have some, even there.
I just wonder why they are so prevalent lately when I literally haven’t seen them in years?I guess we are having a spider mite pandemic too. Sigh.
Gardendaze 
Spider mites are not exactly insects, and it is difficult to say what sets them off. It may have been something as simple and imperceptible to people as a minor adjustment of the heating system. Years ago, spider mites avoided offices in which people smoked tobacco, but seemed to be more likely to move in when tobacco was no longer allowed.
No, I know that they are tiny arachnids but this same office is having infestations of the fungus gnats and I already posted about the aphids we are–or were having.
I would say that it was a problem of where the plants are coming from but they come from at least 4 different sources so that’s not it. At this point, the problem is more likely ours!
And of course I manage the plants almost as carefully as I do my own–but I am not there on the weekends and with things like spider mites, that’s where it can go bad quickly.
Oh well. I have now been away from the office for 4 days. It will be interesting to see what I go back to find.
But I am sure that your theory about the heat is correct. It is my suspicion too.
Karla