Ummm… African ants or European ants?
OK, I’ll assume that each ant only needs a space equal to its horizontal cross-section. When ants swarm (or coöperatively carry something), they don’t leave much space in between. Ants and humans both being approximately uniform density (that of water, in both cases), we can use volume as a proxy for mass. So the question then becomes, how high a column of water, with its own cross-section, can an ant support? If the column height is at least equal to the thickness of a human, then that species of ant can perform the task. Note that this is an absolute column height, not relative: The height of the ant itself is irrelevant. Since all ants are made of approximately the same materials, with approximately the same structural properties, I would expect this height to be more or less constant across different varieties of ants. Smaller ants would, if anything, have an advantage, in that less of the maximum column height is taken up by the ant’s own height, but given that even the largest ants native to the surface of our planet are so small compared to the thickness of a human (I make no claims concerning alien ant overlords nor B-movie ants from miles below the Earth’s crust), this difference should be negligible.
I am, however, unable to determine the value of this column height. The only value I can find on Google (the Handbook of Chemistry and Physics didn’t seem to have an entry) for the compressive strength of chitin is 150 GPa, which would imply a column height of thousands of kilometers, but I suspect that this is a micro-scale measurement, which would not take into account the various failure modes of an actual chitinous structure such as an ant’s body.
However, as the ants get smaller, they must use a larger fraction of their available muscle power to overcome Van der Waals/London/Debye/Casimir forces between their feet and the surface they’re walking on.
And a few ants with tiny little whips.
They weren’t being lazy, they’re the queens; they were wearing teensy tiaras and waving at the crowd as they passed by.
Actually, those guys may have been riding shotgun. In leaf-cutter ants, the smallest ones ride on top of leaf pieces being carried by others in order to ward off parasitic flies that try to lay their eggs on the ants.
Puffed or crunchy?
Most ants are crunchy.