The leaf-cutter bee nest was a waterproof nest.A home of their own choice which is well-planned.It looks like a cigar-tube.It was firmly rolled,well packed and quality intended to protect leaf-cutter bees from rain and, less likely to be attacked by enemies.I don’t see natural ventilation here,it seems to be closely-packed that even the air cannot enter.
Leaf-cutter bees gathered materials from these leaf and the next, you’ll see how well it was cut into circles. Just like humans too, They have different sizes of materials for specific purpose depending on the size on how big and long the cigar-like nest.
Damage on the leaves. Gathering piece by piece would be time consuming.Anyway,They cut it for a purpose and essential to their own survival.