Sometimes it's possible to learn from the past; looking back at old
knowledge with fresh eyes may give new insight. So it is with mealy bugs
and possibly even scale. The once-discredited concept in question is
'spontaneous generation'. Clearly, these bugs simply generate out of
thin air at will, defying any and all attempts at complete annihilation.
They will be with us always; it is inescapable. A never-ending war to
keep the numbers below critical level is the best mere humans can hope for.