Some males fly over or around flowers, literally pouncing on females in order to mate with them. Copulation lasts from a few seconds to a few minutes at most. A male will grasp the female with his legs and sometimes his mandibles in order to hold on while they copulate.

Many female bees only mate once, and males compete to get at them first. Some males even dig down into the soil to encounter a virgin female as she emerges from her larval cell. Most males bees are able to mate multiple times, although Meliponini and Apini male genitalia is torn away during copulation, after which the male soon dies. Some females that regularly mate more than once are found in the genus Panurgus.

Mating System: monogamous ; polygynous ; polygynandrous (promiscuous) ; eusocial

Most bee species are solitary nesters. The female makes a tiny bee-sized chamber for each of her offspring, lays one egg, and supplies the chamber with a ball of pollen and nectar for the baby bee to eat. Then she seals up the chamber and builds another one. Some bees, like bumble bees and honey bees, are more social and build nests or hives. In social bee species, a single queen lays the eggs, while most of her daughters don't reproduce but stay with their mother and help take care of more and more sisters (on average, 60 thousand). Some of the sisters are raised to be new queens, and they and their brothers fly away in the summer to mate and start new nests.

Most bees are solitary nesters. Solitary bees construct their own nests, stocking each brood cell with a ball of pollen and nectar before laying one egg, sealing the cell, and building another. Solitary bees generally dye or leave before their offspring mature. When solitary bees do not leave before their offspring mature, but continue to feed and care for them, they are called subsocial bees.

A colony is made up of 2 or more adult females, regardless of their social relationship. We usually think of a colony in terms of having many workers (all sisters), which do all of the foraging, brood care, guarding, and building, and one queen who is responsible for all egg laying. This is in fact the life of many honeybees (Apis, Trigona, Melipona), and they are considered to be highly eusocial. The queen is completely dependant on her workers, and new colonies are started by social swarms, which fly as a group to a new area never leaving a queen by herself.

Other bees live in much smaller colonies such as bumblebees (Bombini), sweat bees (Halictidae) and carpenter bees (Xylocopinae). Their colonies begin with a single reproductive female who carries out all tasks of nest maintenance including foraging, brood care, and egg laying. After the emergence of daughters, colonial life and a division of labor between the foundress (queen) and her daughters may arise. These colonies are called primitively eusocial colonies. Often, the queen is larger than her workers, but this is not a constant rule.

Bee nests are made up of brood cells, usually with one egg laid in each cell. Most Bombus species however, lay a cluster of eggs together in a wax cell. Cells are made of wax, or dug into wood, soil, plant stems, or mortar. The most complex bee nests are made by Meliponini species, where clusters (combs) of wax brood cells are surrounded by layers of wax or resin food storage chambers, which are further surrounded by layers of wax mixed with resin or mud to protect the colony inside.

Other types of colonies include 2 or more reproductive females who each provision their own egg cells. This is called communal nesting. Most species that make communal nests also have individuals who nest alone. Communal nests can be made up of many species. It is not uncommon to find both solitary bees and wasps nesting communally together. This is especially common in areas where suitable nesting habitat is difficult to find, so individuals nest together in the only suitable areas available. The largest recorded communal nest aggregation was 423,000 bees covering 1300m squared.

Solitary bees tend to line their brood cells with a waterproofing material to protect developing offspring. This material can be wax, pieces of leaves and petals, or varnish-like and made from saliva.

Breeding season: Spring or Summer

Key Reproductive Features: iteroparous ; seasonal breeding ; sexual ; fertilization (Internal ); oviparous ; sperm-storing

Solitary female bees don't tend their babies after they close up their chamber. Bee species that form nests don't seal up the larvae, instead they feed and take care of them as they grow. Male bees never take care of offspring and do very little work.

Parental Investment: female parental care