Why use migratory lids? What's the extra space for?

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.

A few ideas come to mind…more room to hang out when they are bumped around moving the hive; space to fit the air holes; useful space for the bees to store extra honey…

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They were designed for moving hives around with vent holes as Dan has suggested. All my lids are migratory and I am constantly finding comb up there. I have considered using a mat across the top to prevent comb in the roof however this would then obstruct air flow. I believe the head space allows better circulation, bees will circulate the air up the inside of the hive over the top of the frames down the other side and out the entrance. And we all know how important this is to the colony for temperature management and dehydrating nectar. The vents in all my lids are quickly sealed up with propolis and I use to regularly clear them but this was just silly on my part. I figure if they need to vents, they’ll clear them themselves. :relaxed:

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thanks Roderick-

so your hives essentially have no upper ventilation? Do you use screened or solid bottoms? I am curious about ventilation at the moment- I have been working on the theory that you don’t need upper ventilation if you have screened bottoms- but we have had a cold snap in Adelaide over the last week and I have seen quite a bit of moisture on the flow window and flow frames. I am now wondering if that’s OK or if I should have upper ventilation.

I have a feeling that the condensation is normal- and the theory I am following says that the warm moist air should actually be drawn down the sides of the hive as it is pushed by warmer air rising off the cluster in the middle. I think I will have to add more insulation to my roofs to get the most benefit from this concept. Given you have let your holes get propolised up Roderick- perhaps you could experiment and modify one of your hives by insulating the roof as detailed in this article:

Hi Jack, migratory lids without inner covers are fantastic. #1. the bees propolize them down, no need for any tie-downs or bricks. #2. The bees use the extra space when the population blows out, I use that as a guide for swarm control. #3. It does give the bees that little bit of extra room to store honey when everything else is full. I use them in conjunction with vinyl mats. The vinyl mats stop the bees building comb from the tops of the frames to the underside of the lid, making an inspection less messy. Plus the vinyl mat gives a hiding place for beetles so the bees can propolize them in.

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Here is an interesting quote and observation about the ventilation holes in migratory lids from the Australian Beekeeping Guide, 2014, by Russell Goodman ad Peter Kaczynski…page 68 and 69…one of these guys has 51 years experience with bees…

“There is some debate about the use of air vents in migratory
lids during winter. When the ventilator mesh is fixed to the
inside of the vent hole some colonies will seal the mesh with
propolis, thereby restricting ventilation. Other colonies will
choose not seal the mesh, but we don’t know the reason for
this choice. On the other hand, when the ventilator mesh is
fixed to the outside end of the vent hole, the bees don’t seal
the mesh”.

So there you have it. Some colonies seal it and others don’t, I wonder why? And then they all don’t seal it if it is fixed to the outside. How interesting.

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I just requeened a hive- and when I went back in to remove the little queen cage I noted the bees had blocked up all the little holes on it with wax. Certainly this had nothing to do with ventilation., Perhaps they propolise the internal mounted screen vents simply because they view the wire itself as a foreign and objectionable object.

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Yes… that could be a reason but I guess it doesn’t explain the fact that some colonies don’t view the wire as objectionable or at least choose to ignore it. I have 2 ventilated migratory lids (both internal mesh) and one colony took to sealing the holes and the other colony didn’t. Both have hive mat on top of the frames, under the lid.

Amazing how practices differ from country to country. Here in the uk we use flat lids with space above. Crownboard are solid and many people put insulation under the lids. This keeps the crownboard warm so you get no condensation at all

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From what I understand migratory lids are exactly that, a lid for the hive that a) being flush on the sides allows maximum side by side packing on the truck and b) requires the height to allow for the ventilation holes which is necessary when the entrances are closed up when migrating from site to site.
Once at the new site there’s no point changing the lid to a flat one like a telescoping lid as that’s just extra work. As I keep hearing from the beek supply stores, “The commercial guys know best and it’s what they use.” … Telescoping lids? Nup, crown boards? Nope, slatted racks? Huh? Amateurs…tsk tsk tsk. :wink:
I guess it’s easier to pry the lid off too if there’s no overhang.
All the bees here propolized the vent holes shut so I cut a 25mm circle of foam and plug the hole now and follow JeffH’s lead. i also use the extra space in the lid to fit a 25mm thick sheet of insulation.

Aren’t migratory lids used in other countries when transporting hives?

We have them in the US, but they are a different design. The flat part of the lid sits right above the top of the box. The front and back end pieces over lap the front and back of the box. There is no extra space below the lid and you couldn’t fit a vinyl mat under it:
http://www.brushymountainbeefarm.com/10-Frame-Migratory-Top/productinfo/416/

Hi Michelle, I pretty much am doing the same as what Jeff does here, I have put material across the top of the supers to prevent the bees building comb in the roof but not anymore. Half my hives have vented/screened bottom boards and the other don’t, the bees behaviour is still the same, that is, the bees block up the vents in the migratory lid. I do however have an extra layer of insulation by using a pitched roof, it keeps off the rain, hot sun and winter chill.
Yes, the condensation is normal.

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I see a new roof on there too :slight_smile: Keeps the rain out better does it with the bigger boards?

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Sure does, we do get some big downpours at times and this roof really helps. I don’t know why everyone wouldn’t use them.