Hi all
I have been reviewing what is "known" about Late Season Mite Influx, particularly as it relates to robbing. While I have come to believe that robbing is the main path of mite transferral from hive to hive, this suggests otherwise:

> Increases in phoretic mite populations in the fall were expected since brood rearing is declining at this time and fewer brood cells are available to infest. Adding to the phoretic mite population can be an influx of mites on foragers robbing colonies that are collapsing due to high mite populations (Sakofski et al. 1990; Greatti et al. 1992). We did not detect high proportions of FWM during any sampling period as would be expected if foragers were robbing heavily infested collapsing colonies. Though increases in mite numbers due to robbing probably occur, our data suggest other possible explanations for unexpected growth in mite populations. 

> The transfer of mites to foragers is a shift in the mite behavior from attaching to nurse bees for reproduction (Kraus 1993; Kuenen and Calderone 1997) to foragers for possible dispersal. The frequency of this behavioral shift seems to increase in the fall, and might occur for several reasons. Varroa populations are at their highest levels in the fall and brood production is decreasing. There are fewer brood cells to infest so more mites are on worker bees perhaps including foragers (Sakofski et al. 1990). In hives that are highly infested with mites, the chemical profile of nurses and foragers can overlap causing mites to attach to foragers (Cervo et al. 2014). 

> * There are indications that foragers carrying varroa have low returning rates to their own colonies * (Kralj and Fuchs 2006) and could be drifting to other hives. The drifting could be due to parasitism alone or infection by viruses that varroa transmit ...

DeGrandi-Hoffman, Gloria, et al. "Population growth of Varroa destructor (Acari: Varroidae) in honey bee colonies is affected by the number of foragers with mites." Experimental and Applied Acarology 69.1 (2016): 21-34.
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