What Are Mining Bees And Do They Sting?

As I’ve become more interested in bees, I have wondered about the many different types of bees that exist in the world. And once I have noticed a different kind of bees early in the spring. For this reason, I began looking into miner bees and learning about their behavior and their habitat.

So what are mining bees? Mining bees are solitary bees that nest in burrows in the ground.

Do mining bees sting? Yes, mining bees sting but they are tiny and can barely penetrate our skin. Mining bees do not swarm and are generally not aggressive. In the very unlikely event of being stung by a mining bee, it would be a mild sensation. They belong to the genus Andrena, and you may also hear them referred to as digger bees.

Mining bees are fascinating creatures that have interesting nesting habits and pose little or no threat to us. On the contrary, they are of great use to us humans in various ways, so it is well worth spending some time getting to know a bit more about them.

MINING BEE NESTS

Mining bees nest underground by building tunnels. In order to make these tunnels effectively, they prefer sandy or soft soils which are easier for them to dig in. They also tend to choose areas that are reasonably bare so that there are fewer roots for them to work around. They occasionally chose domestic air bricks or soft mortar in old houses for their nests.

Underground nests often consist of the main tunnel with side branches from which small, oval to round cells for larvae that are called brood cells are dug out. Nests are excavated exclusively by the female. She uses her forelegs to dig the main tunnel, and her abdomen and legs to push the soil upward out of the excavated hole.

Though the nest architecture can vary from species to species, the tunnel is usually between 7.8 – 23.6 inch deep, with an entrance around 1 inch wide. After making her burrow, females stock each of these cells with pollen and nectar that they have collected from the early blooming flowers and trees.

Being solitary creatures, these underground burrows are generally dug by a single female. Mining bees may cluster together and create their burrows near each other, and there are some species where females share an entrance but have separate nests underground. From the above ground, this clustering of nests can the impression of social activity. If the nests are left undisturbed, they may be reoccupied again in subsequent years.

MINING BEE LIFE CYCLE

Now we know how mining bees nest, we can look more carefully at their life cycle. The female mining bee begins by collecting pollen and nectar from early spring blooms, which she forms into a ball in each underground cell. This will feed her future offspring. She makes many trips from the nest to the blossoms nearby, and she pollinates hundreds of flowers as she undertakes this task.

The female then lays an egg on top of the collection of nectar and pollen that she has made in the cells of her burrow. She will usually lay around five eggs, and following this, she will die. When the larva hatches it eats the stored pollen and nectar. After hatching, mining bee larvae survive and pupate all summer enclosed in the underground nest. By fall, they mature into adult bees but remain in their chambers until spring, when they dig their way out and emerge into the air.

There can be a huge number of mining bees flying around in spring when all the males are busy with their search for a female mate. At times there can even be hundreds of males flying over the same area where their mothers nested the previous year. The male bees play no part in building the nest, nor in providing food for their offspring. After mating, the female seeks a place to make her nest, and her short life is spent providing for the next generation, and this cycle goes round again.

IS IT EASY TO IDENTIFY MINING BEES?

There are around 450 species of mining bees in North America alone, and they can be difficult to identify by looks alone. Though there are some species of mining bee that look very much like honey bees, overall they come in a range of colors, and while some are quite hairy and fuzzy looking, others have only sparse hair. Since the male bees do not collect pollen, they are not as hairy as the females. The males are also shorter and narrower than the females.

The best way to identify mining bees is by observing their underground nesting habits, which I have outlined above. If you spot tiny volcano-shaped mounds of earth in your flower beds or your lawn that look rather like worm castings, this is another good clue that mining bees are active. Particularly in spring when the mining bees emerge, the presence of they buzzing can be very noticeable. Male mining bees buzz loudly around the tunnels to attract the attention of females.

HOW ARE MINING BEES BENEFICIAL FOR US?

Through their nesting habits, mining bees aerate our soil. Aeration allows the air, water, and nutrients to reach plant roots, meaning they will grow more vigorously. Our garden lawns, in particular, can easily become compacted, meaning that grass roots don’t receive what they need to grow well. The tunnels that mining bees create help to keep the soil fertile and productive. It is also worth noting that the burrowing of mining bees does not harm vegetation or plant roots in any way.

As with all types of bees, mining bees are important pollinators. In fact, they are one of the primary natural pollinators of both cultivated and wild blueberries, which just happen to be my favorite fruit! Although honey bees have been ‘domesticated’ by humans and are now used for much of the commercial pollination of food crops, native mining bees were originally the primary pollinators for early blooming crops such as apples.

DO MINING BEES COLLECT POLLEN FROM JUST ONE TYPE OF FLOWER?

Bees who feed on a wide range of pollens from different plant species are called polylectic bees. They feed on a variety of flowers of all shapes and sizes, and from lots of different plant species. Honey bees are a good example of a polylectic bee, as they prefer to collect pollen from a very large selection of flowers throughout the season.

On the other hand, solitary bees are often oligolectic, and Andrena bees (mining bees) are not an exception to this guideline. An oligolectic bee is one that is picky about what it eats, meaning that it collects pollen from only a select number of plant species. Often these plants are very closely related, being in the same family or sometimes even in the same genus. In fact, some species of Andrena bees are monolectic, meaning they collect pollen from just one single species of plant. For example, Andrena vaga, the grey-backed mining bee, is a species of solitary bee that is found in most of Europe and specializes in feeding only on the pollen of willow trees.

So if a single plant becomes rare or extinct, so does its pollinator. A domino effect of damage ripples through the ecosystem whenever any single element is destroyed.

HOW CAN I PROTECT MINING BEES?

As they nest underground, mining bees are particularly susceptible to damage from aggressive agricultural practices. Methods such as plowing, tilling, disking, and spading can all destroy the mining bee’s nest, and with this, a whole generation of bees can be lost.

Mining bees prefer sites where they have some protection from weather extremes by bushes or trees, so a completely barren site will obviously not be good for them. On the other hand, having everything covered in heavy mulch is also bad for Andrena bees because the females are not able to dig through mulch to get to the soil and build their burrows.

Like all bees, mining bees need blossoms in the garden in order to provide the pollen that they require for food. Female mining bees expend a lot of energy on nest building and collecting provision for their offspring, and therefore require an ongoing supply of pollen and nectar to fuel their activities. Bees benefit from having a diverse and plentiful range of native plants to feed on, as these are the plants that they have co-evolved with. The greater the range of plants you have growing on your land, the more likely it is that you can cater to the needs of a greater range of bees.

You can maintain a bee-safe yard by avoiding the use of pesticides and insecticides which can harm or kill local bee populations. Insecticides readily kill Andrena bees, and herbicides kill the plants on which they are dependent. Maintaining a natural, pesticide-free garden with plenty of plant varieties is the best way to attract and conserve most native bees.

Mining bees tend to be most active for a short period in the spring. If at all possible, leave them alone to get on with their busiest period! The pleasant presence of their buzzing will not last long, so you may even find yourself appreciating it each when it arrives each year.