Hi Peter

You will find most of the published figures on various German websites, the
referances I do not have to hand, but I know there was some published by
Helmut Horne about 15 or 20 years ago.

The technique is not new, but has been used in cold climates for more than a
century.

You speak as if  $17 is a high price to pay for an OMF... you could barely
find a wooden one for that price in UK.

The main reason for using OMF in UK is improved wintering, a slightly later
spring build up is more than compensated for by an accellerated brood
rearing rate which overtakes the solid bottomed controls after a few weeks.

Any IPM effect is purely a bonus... Nobody had heard of varroa when they
stated using OMFs (I think somewhere in New York about 1890).

One difference that may not be appreciated is that many US hives are kept
fairly low to the ground, whereas in UK our floors are mostly 350 mm to 400
mm above ground level. OMFs are not so good low down as a good deal of damp
exists at low levels.

I think this has some bearing on why US hives tend to have additional top
entrances, because they do not get adequate ventilation with the low damp
floors (bottom boards).


Best regards & 73s... Dave Cushman G8MZY
Beekeeping & Bee Breeding Website
http://website.lineone.net/~dave.cushman


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