What physical feature distinguishes an Argentine ant?

The physical feature that accurately distinguishes an Argentine ant is that it has no nodes. Argentine ants are characterized by their smooth, unsegmented appearance between their thorax and abdomen, lacking the distinct bumps or nodes seen in other ant species. This feature is an important identification marker, setting them apart from ants that have distinct nodes that can often help in differentiating between various species.

For context, the other options describe features that are not characteristic of Argentine ants. For example, while some ants may have a heart-shaped head or might exhibit reddish or dark brown coloration, Argentine ants typically display a uniform light to dark brown coloration without a prominent color variation. Furthermore, these ants are usually less than half an inch long, which makes the reference to greater than one inch incorrect. By focusing on the absence of nodes, you can easily identify Argentine ants and differentiate them from other ant species.