They do not deliver honey and are still indispensable: Wild bees dust in hidden many plants and thus ensure a large part of our food. But many species of bees are threatened because their habitat disappears. Hobby gardeners use insect hotels to help. But well meant is not always well done: Read here what matters so that wild bees benefit from the nesting aids.
In Germany there are around 560 types of wild bees with different colors and shapes. Most of them live as loners, not like the well -known honeybee in large countries with division of labor. While only the queen eggs lays eggs at the honeybee, every wild bee is responsible for its reproduction itself. The females create a nest for this and equip it with pollen and nectar for the catering of the offspring. Then put an egg in each other in separate chambers.
What do the natural bee nests look like?
Most German wild bee species build their nests in the ground. They dig tunnels in sand and earth. The guild nesting above ground uses or builds holes in solid material such as plant stems or wood. With clay, tree resin or mud, these insects separate individual nesting chambers. About 25 percent of wild bees have a particularly sophisticated strategy: they wait for other wild bees to build their nests and equip them with meals. Then put your eggs in the nest made at the right moment. They are therefore also called cuckoo bees.
Once the egg is set, it takes another year for most bee species for the offspring to discover the world outside the nesting chamber. First of all, a larva slips out of each egg. This eats the prepared pollen and nectar and thus gets sugar and protein for energy and growth. Separated from her siblings, she then spins a cocoon and reduces her metabolism to a minimum. So she hibernates the cold season. In spring the larva pupates and finally turns into a bee.
Sure wild bees
In search of nectar and pollen, wild bees fertilize a large number of flowers. They ensure a rich harvest and the survival of many wild plants. Around 80 percent of wild plants depend on insects. Wild bees are much more effective than their domesticated relatives: A study shows that wild insects reach twice as high a fruit approach as honeybees with the same number of flower visits. They therefore not only transport pollen, but also in better quality. For example, more strawberries, cherries, rapeseed, coffee and watermelons can be harvested during pollination by wild bees.
Wild bees also serve as food for birds, bats, frogs and lizards. They stabilize and receive ecosystems in which animal and plant species are dependent on each other.
Wild bees are particularly threatened by extinction
Although the great benefit of wild bees is known, around half of the species domestic are threatened. According to the NABU environmental protection organization, 39 wild bee species have even been extinct in Germany. One reason: our landscapes are becoming increasingly monotonous. In the cities, floors are also condensed, bush areas replaced by monastery lawn, small watercourses and dead wood removed. As a result, the bees lack nesting places and food plants that they specialize. In addition, each female laid only about ten to 30 eggs in their short life. If pesticides, changed climate, parasites or fungal attacks affect reproduction, wild bee population is quickly in danger.
Other plant -resisting insect species also suffer massively from the man -made changes in their habitats of the past decades. For example, a study found that the biomass of insects in German nature reserves has decreased by an average of 76 percent in the past 27 years.
Insect hotels – sensible or harmful?
To counteract this development, build or buy insect hotels. With the right technique and adequate materials, insect hotels can offer good nesting places and wintering locations – especially for wild bees such as wooden bees, leafy bees or bumblebees. Other insects such as butterflies, earworms or ladybugs also visit insect hotels. However, you will find better hiding places in natural gardens. The NABU therefore recommends concentrating on the demands of wild bees at insect hotels and no special elements for other insects.
Despite the good intentions, in some cases, however, these are doomed to the animals. Because if the nesting aids are not built properly, many types can be attacked by parasites or mushrooms at once.
What should you pay attention to when buying the nesting aids?
In order to avoid parasite or fungal attack, insect hotels should be made of deposited wood. Glass enables the bee brood to be observed, but does not allow a water vapor. So the bee larvae can melt and die quickly.
However, different sizes in the wood are useful. You should not be drilled on the side of the tree rings, but into the longitudinal wood. This is the name of the side of the piece of wood, which is parallel to the bark of the tree. In addition, the holes should not be too close together. This can prevent cracks in the wood and thus fungi and parasites. An alternative to elaborately perforated solid wood are bundled bamboo sticks or reed pipes that are attached and closed at the rear end.
Regardless of whether it is wooden bores or rods: the tubes should always have a length of at least ten centimeters so that the bees can put enough eggs in. Because the rear eggs are often female and are therefore particularly important for survival. It is also important that the front pages of the pipe entrances are well sanded. Because pointed fibers can slit the wings of the freshly hatched bees and thus lead to their death. A nice especially for insect hotels is a sloping metal roof so that water can flow from above.
Build insect hotels yourself
Since many of the insect hotels purchased are not sufficient for these structural requirements and are also expensive, it is worth picking up even the tool box. The best way to use untreated thick hardwood, for example from ash, beech, hornbeam or oak. The fibers of coniferous woods straighten up and can therefore quickly become a danger to the wings of the insects. Tree slices are also not suitable.
Drill holes with a diameter of three to eight millimeters into the longitudinal wood. The distance between the holes should correspond to at least two to three times their diameter. Drill as deep as possible, but at least ten centimeters. By moving the drill back and forth, the walls become smooth. Then smooth the inputs with sandpaper and knock out the wood shavings. Alternatively, you can also build insect hotels with similar dimensions from bamboo sticks, reed, gate bricks, elderberry sections or paper tubes.
So place and maintain the nesting aid properly
In order for wild bees to set up in the purchased or self -made nesting aid, they should hang sunny and protected from the wind – preferably aligned to the southeast to the southwest. Also make sure that the entrance is not covered by plants. The insect hotel should hang at least one meter to protect against predators. A wire mesh attached at a distance of around 20 centimeters also protects the brood from hungry birds.
Even if you are curious about the success of the nister: Leave the insect hotel as undisturbed as possible after setting up. Because many animals spend a whole year on the inside before they crawl out. Only in mold should you clean or replace the affected corridors in early summer. Anyone who offers such nesting aids for wild bees in their garden should also think about the food supply in the area. Wildflowers such as bell flowers, cornflowers or wild carrots deliver nectar to the bees. A natural garden also offers enough material for the nest building of bees- for example earth, leaf or flower pieces, resin and wood particles.
