Get to know the useful insects in detail

the essentials in brief

• Earth bees or sand bees are bees that live in the ground
• Earth bees should not be fought because they are useful and - sadly - increasingly rare
• Sand bees can be carefully driven away by permanently putting your burrow in the shade and / or slightly moistening the entrances

What are earth bees?

Ground-dwelling bees are called earth bees. They represent the genus of sand bees (Andrena) and are represented worldwide with more than 1,500 species. About 150 sand bees are native to Central Europe, of which 116 species have been observed in Germany.

What to do with sand bees in the garden

Sand bees are often responsible for making holes in the lawn. They can also be used in the substrate of the flower pot or

Flower box(€ 149.00 at Amazon *) Dig passages so that they can be observed on the balcony and terrace in spring. However, there is no reason to combat it, as the insects do not pose a threat.

Only in extreme exceptional cases, for example when the animals nest in large numbers near kindergartens, are deterrent measures into consideration. Relocation of the nests requires a special permit. The survival of the sand bees has the highest priority in all measures and methods. The use of insecticides or home remedies is neither recommended nor necessary.

Moisten caves

If you want to get rid of sand bees, you can gently moisten the cave entrances. Make sure the animals don't drown. When the habitat becomes too humid, sand bees abandon the construction of their burrows and look for an alternative location. This method only works if the females are still excavating. If the entrances have already been sealed, larval development is in full swing. From then on you are no longer allowed to water the breeding grounds, as you endanger the offspring.

Withdraw from the sun

You can also drive away sand bees through permanent shade. Put up a parasol or stretch an awning over the open area that will be colonized by a female. It quickly notices that the living conditions are no longer optimal and breaks off the construction of the cave. This method is also only recommended if the female has not yet closed the entrances. If there are already eggs in the nest, their development is endangered by the lack of warmth.

Protect sand bees

Instead of getting rid of the beneficial insects, enjoy the species in your garden. You can be sure that your garden is one of the most natural and special habitats. If you want to do something to protect the earth bees, you can redesign the garden and balcony accordingly and plant them in a natural way. The more varied the habitat, the greater the chance of successful colonization by sand bees.

Create small habitats

Set filled with sand Flower boxes(€ 149.00 at Amazon *) or pots to offer the sand bees a suitable substrate for building their nests. The vessel should be placed in a sun-exposed place in the garden or on the balcony, as the animals need warmth.

If you have enough space in the garden, you can also use a small area with hollow blocks or Edge quarry stones and these about 50 to 100 centimeters high with drifting sand or loamy sand fill up. As an alternative to stones, you can also use dead wood trunks and thus offer a habitat for several specialized insect species at the same time.

Keep ways open

Small trails in the garden offer particularly good conditions for some species. The floor is kept open by kicks. The bryony sand bee prefers such slightly compacted areas. Think about whether all the paths in the garden really need to be paved. If there is no alternative, you can lay the paving stones with the largest possible joints. Even then, sand bees will still find good opportunities to build nests.

Plant food sources

If the living space is right, all that is missing is equipping the garden with suitable nectar plants. The more diverse you design the garden, the more species feel addressed. In order to attract rarer species into the garden, special forage plants must be available. The bryony sand bee nests in gardens that also contain male specimens of different species of bryony.

What do earth bees look like?

These wild bees look very different. There are very small species that grow to be five millimeters long. The large sand bees reach a length of 16 millimeters. Their basic color varies from black to black-red and can rarely have a metallic sheen.

Most earth bees have furry hair and are recognizable by a light hairline on their abdomen. There are hairbrushes on the hind legs that sand bees use to collect pollen from the stamens. Various characteristics can be used to distinguish between males and females.

Difference between earth wasps and earth bees

Earth wasps show aggressive behavior and appear pushy. Sand bees, on the other hand, are shy and withdrawn. But both insects only sting when threatened. A characteristic distinguishing feature is the hairiness, because earth wasps are often only hairy in places and can thus be clearly differentiated from the furry hairy earth bees.

The insects can be distinguished not only by their appearance, but also by their way of life and nest building. While the earth wasp usually only uses one entrance to the underground cave, the earth bee digs several holes. They usually use the cave for many years. Erdwasps look for new quarters as early as the following year.

Way of life and development

Unlike honey bees, sand bees do not form a state. You live as a loner. The female is solely responsible for building her nest and looking after her offspring. Several females rarely form nest aggregations in the immediate vicinity. However, sharing is the exception. The native species are active in spring and mostly fly between April and June. There are few species that can be observed until late summer.

Nest building

In spring they mate and lay their eggs in tunnels five to 60 centimeters deep. The females dig their own breeding caves by compacting the soil with saliva into lumps and carrying them out of the cave. The clods of earth are piled up around the entrance.

Often clods of earth roll back into the corridor during the construction process, which then have to be carried outside again. Downpours support the construction work. The clods of earth are moistened and harden after drying, creating a stable entrance.

Sand bees do not actually build honeycombs but branch nests that have a vertical main entrance. This branches out into short side passages, each ending in a brood cell. The nest is mostly arranged vertically. The female lays pollen and nectar in each brood cell so that the larvae that hatch later find enough food. An egg is laid in each brood cell before it is closed.

From larva to bee

When the larvae hatch, they feed on the food provided in the shelter of the cave. This is sufficient until pupation, because the mother does not take any further brood care. Many bee larvae such as the common sand bee develop a protective cocoon that they spin from their own glandular secretions.

When the new generation hatches depends on the climatic conditions. If the winters are mild, the adult sand bees come out of their burrows in late summer. In Germany, sand bees do not hatch until the following spring, with males freeing themselves from their cocoons before females. You are trying to mate with these directly.

food

Sand bees are very specialized when it comes to food. On their menu is pollen and nectar from asparagus, finger herbs and Honorary award but also from many daisy plants, umbelliferous and cruciferous plants or butterfly plants. Many species use different food sources. The red-furry sand bee prefers to fly on currant and gooseberry bushes, but also accepts other food plants. About half of the domestic earth bees fly exclusively on certain nectar plants.

• Willow sand bee: Pollen and nectar from willow
• Bryony Sand Bee: specializes in bryony species
• Knautien sand bee: Field scabious, pigeon scabies

winter

Many of the bees native to Germany pupate in late summer, but spend the cold season in the shelter of the cocoon. Only in the coming spring do the insects hatch and crawl out of their burial ground. The parent animals do not survive the winter.

Natural enemies

There are many enemies that sand bees can doomly. Predators benefit from the protein-rich insects, while parasites and fungi attack sand bees and their larvae in a different way.

robber

Predators prey on sand bees as a full insect. These include crab spiders that lie in wait on the flowers of their prey and wait for a visit. Digger wasps can also pose a threat to earth bees. These paralyze the insects with one bite and then suck them out.

Other predators:

• different species of predatory flies
• Types of predatory bugs
• insectivorous birds such as bee-eaters

Parasites

Sand bees are endangered by oil beetles, fan-winged birds and woolen floats. Many cuckoo bees such as blood bees or wasp bees lay their eggs in the underground nests of the sand bees. In this way, cuckoo bees save themselves the search for food, because their larvae feed on pollen and nectar in the brood cells. Such parasitic species have specialized in a few host animals. They are dependent on its existence and continued existence.

Digression

This is how sand bees protect themselves against parasites

Fungi and bacteria

The spread of mold or bacteria in the closed brood cells can have devastating effects. As a result, sand bees are very picky about their nesting sites. They avoid habitats with dense vegetation or excessively wet areas, as these offer optimal living conditions for fungal spores and bacteria. Instead, the insects choose warm and dry environments.

These habitats are unattractive for fungi and bacteria:

• dusty sidewalks
• Low vegetation and sunlit embankments
• loosely overgrown and sunny lawns

Species and habitat

Sand bee species are found predominantly on the northern continents. Most earth bees prefer habitats that have dry and warm conditions. Unlike mason bees, which like to nest in window frames, sand bees look for loose substrates to create a breeding ground. Open soils with sandy spots provide optimal conditions for cave construction. Soils with a high proportion of clay make it difficult to build nesting holes.

Because of their main distribution in sandy habitats, the species got their German name. They differ greatly in their appearance and show differences in terms of flight times, food spectrum and habitat.

Harmful or useful?

Sand bees do not pose a threat to humans, nor are they harmful to other living beings or plants. Even if many people fear the massive appearance of bees in spring, there is no need to worry. Sand bees do not display aggressive behavior. They are shy and do not defend their nests.

The males are unable to sting. Although females have a stinger, they rarely use it in dangerous situations. However, the sting is too weak to penetrate human skin. You can let children and pets play safely in the garden and enjoy the ecological benefits of the sand bees.

Why sand bees are useful:

• pollinate different plants
• increase the harvest of fruits and vegetables
• indicate valuable habitats as they occur in threatened habitats
• loosen the soil

Nature conservation in Germany

Although most native species of sand bees are common, earth bees are protected. The bee population is falling dramatically. When the pollinating insects die out, many plants have no chance to reproduce. According to the Federal Nature Conservation Act, it is forbidden to catch, disturb or kill animals. The protection also applies to the nests, which may not be removed, destroyed or relocated without a special permit. Some Andrena species are already endangered as their habitats are becoming scarce. Andrena marginata is even endangered.

Changes in environmental conditions and human interventions have devastating consequences for sand bees.

Sand bees in danger

There are still many species of sand bees in Germany, but the situation can change quickly. There are natural nesting sites on poor dry grassland with a sandy subsoil. Forest fires, floods or landslides continuously create open locations that are populated by sand bees. More and more of these habitats are being destroyed so that the insects have to reorient themselves. They colonize locations close to humans. But human interventions ensure that such habitats also become scarce. Gravel and sand paths are covered with tar and areas are ameliorated.

This endangers sand bees:

• Shortage of food supply
• Ignorance of the people
• monotonous garden design

frequently asked Questions

Do earth bees make honey?

Sand bees collect pollen and nectar, but they do not produce honey from it. The insects use plant-based nectar donors as a source of food for themselves and to create a food basis for their offspring. To do this, they equip each brood cell with pollen before laying their eggs in order to lay their eggs on them. The larvae have to feed on this until they pupate, because they do not leave the cave until the following year.

When do earth bees hatch?

The larvae hatch a short time after oviposition if there is sufficient warmth in the brood cavity. They remain in the shelter of the underground passages until pupation and usually overwinter in their cocoons. Only in the following spring do the young insects bite through their protective cover and free themselves from the closed earth passages. Most species of sand bees fly between April and June.

Are earth bees dangerous?

There is no danger from the very differently colored species. Sand bees do not defend their nests. The female leaves this after laying eggs. If it gets into a dangerous situation itself, it tries to defend itself. However, these defense methods are completely harmless to humans.

Do earth bees have a stinger?

Males are stingless. Only the females have a sting with which they can sting in case of danger. The sting is not dangerous for humans because the delicate sting cannot pierce the skin. You don't have to worry about a sting from the frolicking dog either.

How old do sand bees get?

After males mate, they die. The time-consuming part of life now begins for the females, because they build the nest cavity and provide the individual brood cells with food. About four weeks after the mating activities, the females also die. The larvae overwinter in their cocoons to crawl out of the nest cavity in the coming spring. Then the drama begins all over again.

What do you do against earth bees?

For reasons of species protection, control is out of the question. Removing and destroying the nests is just as punishable as catching and killing the insects. Relocation requires a special permit.