It seems in Australia and many other places most beekeepers use what they call ‘migratory lids’ where there is no inner cover and a gap of maybe two inches in the roof. I am wondering why? I watched a local beek inspect his hives and methodically set about cutting out the comb in the roof space. What is the advantage of having that extra space above the frames? Is it to give the bees more room to hang out and reduce congestion- or is it for airflow- or both- or what exactly?
I have a few Nuc boxes with this type of lid and am wondering about it.