>Ari, any chance of a citation for the above study? 

Siira, Siira & Korpela 1999. Beekeeping in Northern Finland. Public. Agric. 
Res. Centre of Finland ISBN 951-729-545-6  In Finnish, short abstract in 
English (my writing here has more info) 

Questionnaire for beekeepers in two years. Northernmost beekeepers around 
arctic circle, southernmost 200 km south of circle. 244 beekeepers operating 
3071 beehives. Mainly hobbyist with average of 11 years of experience. 

44% carnica , 41 %  Italian bees in insulated Langstroth boxes. 

Most common reasons for winter losses queen failure and moisture in hive/ 
starvation.

Weakening of ventilation (solid bottom, wrappings, small entrance) increased 
losses. Also wooden equipment had bigger losses than ESP. Bigger losses with 
diluted winter feed ( 50 % sugar compared to normal 65 % )  Differences  in 
total losses by these factors typically about 5  %   Average losses about 15 
%.

Entrance opening lenght  reduced to 1-5 cm ( 2,2 cm high)- losses 25 % 
Entrance opening more than 15 cm ( = totally open)  - losses 14 % , - exactly 
same results for 2 years  

No difference of honeycrop ( average 38 kg) from beerace or hive type. The 
honeycrop was also same for the new colonies from previous summer and for older 
colonies that had wintered also before.

No effect to honeycrop from spring feeding with sugar or pollen, or by opening 
feed frames with uncapping fork in spring.

 Ari Seppälä

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