Bee-Havior
We often think about “busy bees” gathering nectar for a colony ruled by a queen. But most bees don’t live this way. There are four types of bee social behavior:
A solitary bee.
Solitary bees
Over 75% of bees are solitary. Solitary bees live and raise their offspring alone. Each female bee builds and defends her own nest, lays her own eggs, and gathers nectar and pollen for her offspring without the help of any other bee. She often dies or leaves the nest before her offspring emerge. Most solitary bees nest in the ground or in dead wood.
A parasitic bee.
Brood parasites
Around 15% of bees are brood parasites. Brood parasites such as cuckoo bees don’t gather pollen, build their own nests, or collect food. The female cuckoo bee enters the host nest, usually when the host bee is out foraging, lays an egg in the nest, and leaves. When the parasite’s larva hatches, it kills the host offspring and eats the pollen ball that was originally left for the host bee larva. Nasty business! Brood parasites often look like wasps. Their larvae have huge mandibles used to kill host larvae.
Social bees
Only about 9% of all bee species are social. In social colonies, many bees live in the same nest and each female plays a distinct role. Workers gather pollen and nectar for the colony, defend the colony against intruders, and cannot reproduce. The queen produces offspring, but doesn’t forage or leave the colony. This division of labor is called caste polymorphism.
Two highly social bees.
Highly social bees
Honey bees and stingless bees always live in large colonies with a queen bee that lays most of the eggs and lots of workers that make honey and take care of the nest. the queen is unable to live on her own and care for herself or her offspring. New nests are established socially by swarms.
Two primitively social bees (bumblebees).
Primitively social bees
Bumble bees, many sweat bees and carpenter bees live in small temporary colonies where there is division of labor (egg-layers vs. foragers) among cooperating adult females of two generations. New colonies are started by a single female who constructs a nest, forages, and lays eggs. Only after the bee’s first brood emerge can colony life begin.
Social parasites
Social parasites make up a tiny slice of bee diversity, only about 0.5%. Social parasites attack the nests of social bees. A female social parasite enters the nest of a social queen, attacks or evicts her, and then replaces the queen. The parasite queen bee then lays her eggs. The worker bees of the social species foster the parasitic offspring, unaware of the takeover.
What about male bees?
Female bees seem to do all the work! Males don’t build nests, sting, or gather food. Their lifespan is often very short compared to female bees. Male bees exist only to reproduce. Male bees use many tactics to maximize their attractiveness to mates. Males may spend a lifetime gathering bouquets of scent to court a female. Some engage in fierce battles over females. In many species, female bees have an active role in choosing a mate.
How do bees find their nest?
The bee shown in pink is leaving the nest on her orientation flight. The bee shown in blue is returning to the nest along the same path flown on the outgoing flight. By flying the same trajectory to and from the nest, solitary bees can accurately re-locate their nests.
When nest-building bees forage for pollen and nectar, they must be able to re-locate their nest each time. To do this, bees (and wasps) fly an “orientation flight” as they leave the nest on the first trip of each day. This flight involves a slow, zig-zagging, looping departure from the nest. During the orientation flight, the bee flies backwards facing the nest entrance and on each arc of the orientation flight, the bee gradually gets further and further from the nest and higher and higher above the ground.
What is she doing during this flight? Based on careful experiments conducted by Nico Tinbergen in the 1930’s we know that during these flights, bees and wasps are learning the landmarks around the nest. As she scans the ground on each looping arc, she is memorizing the landmarks, including stones, plants, surface irregularities, and other features, so that she can re-locate the nest.