Randy asks: do you know of any published trials, that compared wintering in top-vented vs control unvented colonies?

INGEMAR FRIES (1982) OUTDOOR WINTERING OF HONEYBEES IN TOP-VENTILATED HIVES
Journal of Apicultural Research 21(4) : 212-215

Summary
The effects were investigated of wintering bees in migratory hives (2 types) with top insulation, with and without top ventilation. The study lasted three successive years, with a total of 112 colony winterings. The top ventilation made no significant difference to winter loss of bees, food consumption, colony size in spring, or honey yield next season. The ventilated hives showed a substantial reduction (P<0.001) in the occurrence of damp and mould in the hives, as assessed on a four-point scale.

see also
TIBOR SZABO (1985) 
THE THERMOLOGY OF WINTERING HONEYBEE COLONIES IN 4-COLONY PACKS AS AFFECTED BY VARIOUS HIVE ENTRANCES
Journal of Apicultural Research 24(1) : 27-37 


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