This may be of only passing interest, but here in South Africa, I typically
put trap hives out with a strip of foundation of only about 25mm wide,
cemented with hot wax into the groove under the top bar of brood
(deep)  frames. This allows bees to cluster properly for warmth in
winter, is certainly economical, and minimises heat damage when a
box remains unoccupied for some time.

Anyhow, the point is, given Allen's comment of giving the bees "what
they want,"  that very soon after drawing the foundation, the bees revert
to "natural size" cells. That is, the cell size that they want - they're
drawming comb in open air. When all the frames are drawn, even
those with "solid" brood cells inevitably have some honey/pollen
stored near the top of the combs. This would mean that most brood is
in fact raised in cells built the size that the bees want.

I have no idea as to whether this helps the wild scutellata swarms so
trapped to resist varroa, hive beetle, etc., etc. But on recent detailed
inspection of great numbers of wild swarms captured in the past few
months, starting with those minimised strips of foundation, the
presence of disease/pests was minimal. Certainly, none of the
colonies needed treatment for anything. And there was zero evidence
(repeat: zero) of AM capensis laying behaviour, but that is another
story.

Barry Sergeant
Kyalami
South Africa