The stuff on the bottom board corflute

[Bin Chicken]

Hello fellow beekeepers. Hope everyone is safe.

I have two new flow hives with screened bottom boards and corflute slider. Both colonies are new and still establishing slowly. I'm in the Perth hills.

I'm noticing that on one of them, I have black debris. I tried to have a look with a magnifying glass but I couldn't identify anything in particular. I inspect these hives weekly or forthrightly and I haven't noticed any pest or disease that I can identify.

Any ideas from the photos supplied? (I was on the Flow forum but didn't like the egos so trying my luck here)

First two are from first hive, the other two from second hive

[BeeMaster2]

Bin,
It looks like the bees are cleaning out old comb.
You did not mention how long the bees have been in this hive. It sounds like you are saying it is a new hive but the picture says different.
Jim Altmiller

[wet bee]

Gday Bin
Apart from normal hive debris, it looks like you have a bit of chalkbrood in the 2nd hive. Bit hard to tell looking at the first pics.
I would make sure your hives are well ventilated .