What is the main characteristic of the pavement ant?

The main characteristic of the pavement ant is its hairy blackish-brown appearance. This description aligns with the pavement ant's physical traits, which include a dark coloration and a somewhat hairy texture, helping to identify this specific species among the many types of ants. These traits are crucial for recognition in both casual observation and scientific study.

The other options do not accurately reflect the attributes of pavement ants. For instance, the species is not the largest, as there are many other ant species that are much larger in size. It also does not have a diet limited to proteins; pavement ants are known to be omnivorous, feeding on a variety of substances, including sugars and fats, in addition to proteins. Lastly, pavement ants typically build their nests in the ground, often in cracks on pavement or sidewalks, rather than in high trees, which is characteristic of other ant species that may exhibit arboreal nesting behavior.