Insulated telescopic covers

[Occam]

I've seen Jim and others recommend using foam board on the cover to lessen heat in the hive and help alleviate bearding. Is that used on the outside of the cover or inside. If it's inside won't the bees chew it to pieces? Or should I tack insect screen over the hole in the inner cover so they can't get to it?

[BeeMaster2]

I use screen top boards on all of my hives. Makes it real nice to bee able to check on the hives without disturbing them. I try to use insulated boards that have metal foil on them. Then you just have to make the board tight inside the cover. I also put insulation inside of the screen top board. Without it the bees will beard when it is hot. They can control the temperature better if the hive is closed up with only a small hole or it is open on the bottom.
Jim Altmiller

[cao]

Between inner and outer cover.  I think jim uses screened inner covers so bees can't access foam.  For standard inner cover you would need to cover hole with something(screen, wood, aluminum tape, etc).

[Occam]

Rightnon, thanks! With warmer temps kicking up I wanted to make some refinements. I have some foam board left over from my long hives and thought I'd use it. Also have some leftover polycarbonate panel from a cold frame I built I could use as a barrier to the foam board.

[FloridaGardener]

I bought a $20 4ft x 8ft sheet of pink Owens-Corning R-5.  It's about an inch thick. 
I use it over screened inner lids, inside telescoping covers. 

My screened bottom boards are raised on attached pressure-treted cleats to allow a West Beetle tray.
So I also cut foam board sized to slide between the cleats instead of the trap, great to keep nucs wam in early spring. Or to protect big hives from chill during tropical storms.

And I cut some to go inside a feeding hive body rim, when transitioning a nuc to a 10-frame.  I used a 4" hole saw to drill the center of the foa board. This goes on top the unscreened inner lid. When the quart jar feeder is on, the bees drink syrup instead of chewing the foam.  They seem to prosper with the extra thermoregulation.

And  a larger piece of foam is useful for putting under a hive body when pulling brood.  When new bees fall off, the foam catches them and it's a breeze to lift.  One light lift of the board and light tap...and fallen nurse bees slide into the hive at close-up.

[Occam]

While doing my inspection today (first since they swarmed a few weeks back) I added a layer of .75" foam board followed by a layer of polycarbonate. A couple poultry netting staples pressed into the sides hold it all in place until they propolize it. It now sits slightly higher than the inner cover so I placed a rock onto it. This hive propolis heavily, it's always a solid pry effort to remove the lid.

[Acebird]

If the foam in put on top of the cover it doesn't diminish the function of a telescoping cover.