David Eyre wrote:
 
>I have been advocating the above for many years. It would appear that
>upwards ventilation is a European idea. Why it is frowned on in North
>America, I for one fail to understand!
>        I remember reading in one of the older bee keeping manuals (I
>believe A.I. Roots) ventilation being discussed and at the time it
>was considered necessary. How come it's fallen out of favour?
 
I wonder.  Actually, Langstroth's orig. hive had an upper vent/entrance.
He must have considered it important from the get-go.  Some of the factory
inner covers have had a tiny port in the rim, but this is not very
substantial.
 
During winter all our outer covers are raised about 3/8" above the inner
cover rim with wooden risers (sort-of like the matchstick idea) a la Manley
and this keeps everything nice and dry -- no moldy brood combs or soggy
bees.  I think it is helpful in summer, too, for the air flow.
 
As far as wax moths go, even if they get in through an upper entrance, say,
on a cold night, still, any colony strong enough to need the extra entrance
will be able to deal with any intruding moths.  On a really weak colony it
would be a concern, though.