Bees are flying insects belonging to the order Hymenoptera, distinct from their wasp and ant relatives primarily due to their vegetarian diet of nectar and pollen. With over 20,000 known species globally, this vast group exhibits a wide range of behaviors and lifestyles. To simplify this enormous diversity, scientists categorize bees based on their social structure, which dictates how they nest, reproduce, and organize their lives. This classification reveals three fundamental ways a bee can live: alone, in a complex society, or as a parasite.
Solitary Bees
The majority of the world’s bee species, approximately 90%, are classified as solitary. In this lifestyle, every female is a fertile individual who builds and provisions her own nest entirely alone. There is no queen, no worker caste, and no cooperative care of the young.
A solitary female creates small, individual brood cells, each provisioned with pollen and nectar upon which she lays a single egg. She seals the cell and repeats the process until the nest is full, often in tunnels excavated in the ground, wood, or plant stems. Examples include Mason bees, which use mud to cap nests, Leafcutter bees, which use pieces of leaves, and Mining bees, which nest underground.
Solitary bees are efficient pollinators, often surpassing the effectiveness of social species. They do not have the specialized pollen baskets (corbicula) found on social bees. This means pollen loosely adheres to their hairy bodies and is easily dislodged onto every flower they visit. A single Red Mason bee, for instance, can provide the pollination service equivalent to over one hundred honey bees.
Social Bees
Social bees, which include the well-known Honey bees and Bumble bees, live in organized colonies with a clear division of labor, a structure known as eusociality. This system is characterized by overlapping generations, cooperative care of the young, and the presence of specialized castes. The vast majority of a social colony consists of sterile female workers who forage, build, and defend the nest, while a single queen is responsible for all reproduction.
Honey bee colonies are highly eusocial and perennial, meaning they can survive for many years. They build large, intricate nests containing tens of thousands of individuals. They store vast amounts of honey to sustain the colony through the winter months.
Bumble bees are considered primitively eusocial, as their colonies are annual, meaning they last for only one season. A new queen emerges in the spring to start a small colony, which contains only a few hundred individuals at its peak. Unlike honey bees, bumble bees are also capable of “buzz pollination,” where they vibrate their flight muscles to release pollen from flowers that other bees cannot access.
Cleptoparasitic (Cuckoo) Bees
The third group of bees consists of the cleptoparasites, commonly referred to as Cuckoo bees, which have evolved a parasitic lifestyle. These bees do not build their own nests or gather food for their young. Instead, they rely on the provisions collected by other, usually solitary, bee species.
A female Cuckoo bee sneaks into the provisioned nest cell of a host bee and lays her own egg. The Cuckoo bee larva that hatches uses its large, sickle-shaped mandibles to kill the host egg or larva before consuming the provisions. This cuckoo lineage, such as the genus Nomada, has independently evolved this strategy multiple times across different bee families.
Cuckoo bees have lost the specialized structures used for pollen collection. They lack the dense, branched hairs known as the scopa on their legs or abdomen, which is a defining feature of pollen-collecting bees. This lack of hair gives them a smooth, hairless, and wasp-like appearance.