What characteristic of Argentine ants makes them a problem in structures?

The characteristic that makes Argentine ants problematic in structures is their ability to enter through small cracks. Argentine ants are known for their adaptability and persistence, allowing them to exploit tiny openings in buildings. This capability enables them to invade homes and other structures, searching for food and nesting sites. Once inside, they can establish large colonies and can be difficult to eliminate due to their reproductive strategies and social behaviors.

While building nests underground and having a strong scent trail are aspects of their biology, they do not directly contribute to the immediate problem of infiltrating structures. Although being attracted to light is a behavior seen in some insects, it doesn't specifically explain their ability to invade human habitats like small cracks do. Thus, the ability to enter small openings is what makes Argentine ants particularly troublesome in urban environments.