Foundation on frame now dark

[Gregs]

Newbie here. I have a hive that I'm going to requeen in a few days. The hive hasn't progressed at all since I started it as a 5 frame nuc on June 6. My other hive is doing great.

One thing I've noticed is that on one of the frames (waxed Ritecell) the entire foundation sheet is now a dark brown. It isn't built up comb - there are no bees on it. It is one of the outermost frames. Any idea what that could be? Thanks.

FWIW, the weather here in Vermont has been rainy and cool as all get out.

[Scadsobees]

Could be the bees tracking pollen and propolis all over the place.

My guess, though, from the cool, cloudy, and probably wet weather would be a thin layer of mold that will form on the thin wax on the frame.

Nothing to worry about unless you are seeing things like a lot of chalkbrood.  The bees will clean the frame when they need it and draw it out fine.

Rick

[Gregs]

Thanks!