About Bee Nests

Bees may nest in the ground, inside a hollow twig or snail shell, or they may create an elaborate structure from wax hexagons. Whichever form the nest takes, there will be brood cells, in which larvae are raised. 

No matter the species, nests are created by females, and depending on the level of sociality of that species, either a single female locates a suitable site and constructs the nest cells herself, or there may involvement from other female workers.

Bee Nest Structures

Soil excavators
According to Christina Grozinger & Harland Patch; (authors of The Lives of Bees A Natural History of Our Planet's Bee Life)¹, 70% of bee species build their nests in soil, which is believed to be the earliest evolved form of nest building in bees.

Nests are excavated by females using their mandibles (jaws) and forelegs, by solitary bee species.  These nests take the form of tunnels, sometimes angled, and perhaps with side chambers, depending on species.

Nest walls are usually lined with a protective coating, and  nest cells are provisioned with food for larvae that will develop from eggs laid by the female.

A variety of species from different bee families are known to dig in the ground to create nests, including mining species, but also some leafcutters and members of the genus Anthophora (flower bees).

Wood excavators
Some bee species excavate their nests in wood or pithy stems.  This activity is undertaken by female bees, and they have specialised robust mandibles for the task.

Large carpenter bees (genus Xylocopa) are well-known for their nest-building activities, which can occur in tree trunks or human-created structures, such as fence posts.  Nests can be extensive, with multiple galleries, and with cell partitions made from excavated sawdust.

Small carpenter bees (genus Ceratina) typically target soft canes, berries and roses, and other pithy stems.

Cavity nesters
Pre-existing cavities may also provide suitable homes for bees, for example:

• existing crevices or beetle holes in the bark of trees or wooden structures, or hollow plant stems (popular with various leafcutter and mason bee species); or even empty snail shells.
• an empty bird box or an abandoned mouse hole (possible choices for bumble bee species).
• large cavities provided by caves, hollow tree trunks or empty chimneys may be used by by honey bees, which then fill the space with wax combs.
  

Above-ground nest builders
Such nests consist of cells constructed out in the open rather than in a cavity. 

For example, the nests of Apis florea (Red dwarf honey bee - a species found in the Asian tropics) are constructed from wax comb attached and hanging from the branches of trees.  Similarly, the giant honey bee, Apis dorsata builds its honeycombs high in a tree (colloquially referred to as a 'bee tree').

This nest-building habit is in contrast to the Western honey bee, Apis mellifera, which would seek a hollow trunk or cavity, and is often housed by beekeepers in specially constructed hives.

However, not all above-ground nests created by bees are large structures, but in their own way, they may be impressive. 

For example, some species of the Dianthidium genus (family, Megachilidae) are also known as 'pebble bees'.  They construct nest cells from tiny pebbles 'glued' together with plant resin, soil and sand, on exposed surfaces and twigs.

Do all bee species create nests?

Some species manage to produce young without ever constructing nest cells or providing for their young.  Cuckoo species may either co-habit with a host, relying on the host and her offspring to provide for her young.  Forms of this behaviour are evident among bumble bee cuckoos.

On the other hand, a number of cleptoparasite species (such as Sphecodes - blood bees) surreptitiously enter target host nests, and lay an egg in a cell provisioned with food intended for the hosts young.  The adult bee will either destroy the host's eggs itself, or the parasite's young will develop more quickly inside the cell than the host larvae, which it will then destroy, and consume its food.

References

1. - Christina Grozinger & Harland Patch; The Lives of Bees A Natural History of Our Planet's Bee Life - Princeton University Press 2024.

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