Hi Karl:

I have used 3/4" fir plywood for hive bodies and feeders for about 5
years.  The hive bodies were assembled with lamello biscuits and
waterproof glue. The edges were sealed with thinned spar varnish and the
outsides were given three coats of latex enamel. They seem to hold up as
well as the conventional ones made up of pine with nailed finger joints.
The bees seem to like them.

I have not had any luck using plywoods other than the fir. The glue used
in the manufacture of the plywood seems to be the crucial thing. It is
also worth noting that our climate is quite dry and we have no problems
with rot or insects.

Best regards,

Donald Aitken
Edmonton Alberta Canada