Which bees dig in the ground? Bees may be observed digging in soil, sandy banks and lawns. There are even some species which sort the grains of soil in their nests!
There may be variations between species, however, they may use their front legs, with the aid of their mandibles to losen dirt, then ‘shovel’ the dirt away with their legs. The pile of dirt or sandy soil may then become a little mound surrounding the nest entrance.
It depends on the species, but mostly, it is in order to create a nest. In some cases, however, parasites may be the issue, or hibernations. You can read more about this on my page: Why do bumblebees dig?
Here is a summary of some of the species:
Mining Bees – Andrenidae
Andrenidae are a very large group of bees, and there are about 4500 Andrenidae species across the world.
Andrenidae nest in the earth, but there is great variety: whilst some bees dig shallow holes – perhaps just a few inches, others bees dig deep tunnels. Wilson and Messinger Carril, in their book The Bees in Your Backyard: A Guide to North America's Bees mention that scientists studying Andrena haynesi in the Utah desert dug up a nest that actually reached 9 feet underground! They point out that this is the equivalent of a 6-foot-tall human using his hands to dig the depth of four football fields in the earth, thus drawing attention to the fact that to dig 9 feet underground is an incredible feet for a small insect!
But what about the rain?
When these bees dig in the ground, don’t the tunnels leak? It turns out that, according to Wilson and Messinger Carril, Andrenidae line their nests with a waterproof substance secreted by the female. This is so effective, it can even protect developing bees in seasonal lakes, such that the adults are able to emerge again safely once the lake has dried up. This substance also not only protects the nest from moisture, it helps protect these ground nesting bees from soil bacteria.
Again, according to the fantastic book by Wilson and Messinger Carrill, some species actually sort out the grains of soil, according to coarseness. The finest particles are used by the females for creating smooth walls around the cell containing an egg. Larger particles are used to block the entrance to the nest at night!
The Apidae family comprises about 5700 bee species and 200 genera around the world. Some of these (but certainly not all), are ground nesting bees, including, for example, bees from the genus Emphorini, Eucerini, Centris – found in North America.
In North America, bees from the genus Habropoda and Anthophora, are also referred to as 'Digger Bees' (although Anthophora furcata nests in twigs instead of the ground) – and they also belong to the family Apidae.
In the UK, some Anthophora make their nests in soil, banks, cliffs or walls.
Bombus - Bumblebees
I have a whole page on this website covering why bumblebees dig in the ground (specifically because I was asked the question during a talk). In the case of bumblebees, they may dig holes in soil to hibernate, but parasites can also cause a bumblebee to dig in the soil. How can you know the reason for the digging? You can read all about it on this page.
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