Mining Bees in the Garden: Habits and Conservation of the Genus Andrena

Key Points at a Glance

• Mining bees (Andrena) are solitary wild bees that build their nests almost exclusively in the ground.
• Creating open, vegetation-free patches of soil is the most effective way to support these specialised pollinators.
• In July, many species are in the resting phase of their larval development underground; soil disturbance should therefore be avoided.

The Biology of Mining Bees (Andrena)

In Central Europe, the genus of mining bees (Andrena) is represented by over 100 species. Unlike social honey bees (Apis mellifera), these wild bees live solitarily. Each female provisions her own brood in underground tunnels. Especially in spring, species like the Grey-banded mining bee (Andrena flavipes) or the Early mining bee (Andrena vaga) define the character of our gardens, as they often appear in loose aggregations—that is, loose groups of nests.

The biology of these bees is closely tied to the availability of nesting sites. Mining bees require sunny, vegetation-free or sparsely vegetated soil patches for their nests. The soil should have a certain structure to prevent the tunnels from collapsing. Loamy to sandy soils are preferred.

Specialisation in Foraging

Some species of mining bees are highly specialised in their choice of pollen sources; this is known as being oligolectic. This means that they depend on the pollen of specific plant families or genera to raise their larvae. If these plants are missing, the population cannot be sustained.

Practical Tips for Conservation in the Garden

1. Create open soil areas: Remove the turf in a sunny area to create vegetation-free patches. This gives the insects access to nesting grounds.
2. Avoid soil cultivation: Since the brood is located in the ground, digging or hoeing in summer is fatal. Refrain from these activities completely in nesting areas.
3. No chemical products: The use of insecticides or synthetic fertilisers destroys soil chemistry and directly harms the larvae. Furthermore, strictly avoid peat-based compost, as the destruction of peatlands threatens the natural habitat of mining bees.
4. Plant selection: Supplement your garden with native wildflowers. The white bryony (Bryonia dioica) is particularly essential for specialised species like the bryony mining bee (Andrena florea).
5. No mulching: Avoid bark mulch on nesting areas. Mining bees need direct contact with the mineral soil to dig their nesting tunnels.

Common Questions About Mining Bees

Are mining bees dangerous to humans? No. Mining bees are extremely peaceful. Their sting is too weak to penetrate human skin. They do not defend their nests.

Should I be worried if there is a collection of nests? No, these "colonies" are harmless gatherings of individual bees. Each female has her own entrance. They do not form a colony and do not have a queen.

Why don't the bees use my insect hotel? Mining bees are ground-nesters. They require open, structured soil. Insect hotels made of wood or reeds are unsuitable for this genus due to their design.

Frequently Asked Questions

Are mining bees dangerous to humans?

No. Mining bees are very peaceful. Their sting is too weak to penetrate human skin, and they do not defend their nests.

Should I be worried about nest aggregations?

No, they are peaceful solitary bees. Each female digs her own tunnel. They do not form a colony and do not have a queen.

Why don't mining bees use insect hotels?

Mining bees are ground-nesters and require open, sunny soil for digging. Wood or reed structures are unsuitable for this genus.

Main article: Ground-nesting wild bees in the garden: Protecting their habitat