LoL. This sounds like me (w/ a few differences on the particulars). I fight & conquer one nasty threat to my CPs - do a multi-month 'sigh', relax and then ..... bam. I get hit with something I've either never had or at least, not seen for years. Gotta stay vigilant ....I used to have a very uncomplicated plant life. I never had any problems other than the squirrels. Now I have "white-out", aphids and mealy bugs. And an occasional scale.
Based on the fairly regular periodicity & the devastation to my plants (& my psyche), I'm mulling the possibility of stopping incoming plant trades and just trading for seed or sterile flasks... I doubt that I'll actually get to this point but each time this occurs, it becomes more of a realistic option - especially as my collection has over 95% of the Sarrs I've ever wanted ....