> since we have so many authorities pointing towards the existence of 'mite bomb' certainly it must be true?  might oakum razor apply here... in that perhaps a simpler explanation might be worthy of consideration?

What on earth could be more simple than this? A sudden influx of mites in late summer = failing colonies in the neighborhood. The only thing simpler would be "spontaneous generation." Pretty sure that Occam disallowed magical explanations. 

The only way to confirm such an effect would be to have universal bee inspection; track which colonies are treated, which are not; and map the impact over time of this particular dynamic. The obstacles for such a study seem insurmountable.


See:
Autumn Invasion Rates of Varroa destructor (Mesostigmata: Varroidae)
Into Honey Bee (Hymenoptera: Apidae) Colonies and the Resulting Increase in Mite Populations
EVA FREY AND PETER ROSENKRANZ.  (2014) J. Econ. Entomol. 107(2): 508-515

The honey bee parasite Varroa destructor Anderson & Trueman can disperse and invade
honey bee colonies by attaching to “drifting” and “robbing” honey bees that move into non-natal
colonies. We quantified the weekly invasion rates and the subsequent mite population growth from
the end of July to November 2011

Because of anticipated changes in climate leading to
higher autumn and winter temperatures in temperate
regions (Linderholm 2006), we will increasingly be
faced with conditions that support re-invasion into
colonies of Varroa mites in autumn and their reproduction
therein.

At least in regions with high bee densities, this will
significantly increase the number of mites within the
region and most likely, as a consequence, the Varroa
reinvasion pressure and horizontal transmission of
Varroa mites between colonies. 

high bee densities combined with ineffective treatment
will not only increase the risk of colony damage
but might also select for more virulent Varroa mites.

PLB

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