What is a distinguishing feature of solitary ground bees?

Solitary ground bees are characterized by their unique nesting habits, which involve building nests directly in the ground. Unlike social bees that live in hives, solitary bees do not share their nests or have a colony structure. They typically excavate small burrows in the soil, where they lay their eggs and provide food for their larvae. This nesting behavior is a key distinguishing feature that separates them from other types of bees, such as those that nest in wood or are social in nature.

While some species of bees may exhibit metallic colors, it is not a universal trait of solitary ground bees, as they can come in various colors and patterns. Additionally, solitary ground bees can display defensive behaviors when their nests are disturbed, contrary to the notion that they lack defensive behavior. Thus, the correct choice highlights their specific nesting behavior as a fundamental characteristic.