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Molehills and wild plant flower strips for wild bees and beetles: How farmers promote biodiversity in the fields.
They can be created as a cost-effective and short-term alternative to hedges. Especially where the mosaic structure is missing in the cultivated landscape, they are a good solution: Beetle Banks. A low earth mound, with a wildflower strip or field margin. This combination is intended to provide habitat and food for wild bees and beetles. The earth mound, which quickly warms up, mimics a natural cliff edge and creates opportunities for nesting and hiding places. Originally, this technique comes from cereal cultivation. The walls were positioned on large fields to provide insects with a refuge space.
The ecological structural diversity is increased and the diversity of native animal and plant species is promoted and preserved. Living conditions for arthropods (insects, spiders, millipedes, etc.), including pollinators, beetles, and spiders, are improved. Natural pest control is achieved by the settlement of predatory insects such as ladybugs or parasitic wasps. The fast-warming surfaces create nesting, hiding, and overwintering opportunities, and the food supply is enhanced by an increased number of flowers. The linear networking of habitats is promoted, enriching the landscape and ensuring the pollination of wild and cultivated plants.
The construction of the walls usually takes place in the fall during regular soil cultivation. Often, when plowing, the soil is compacted in the opposite direction. A potato ridge former can also be used. Subsequently, the area can be treated with a herbicide. Sites with high weed pressure are rather unsuitable for the Beetle Bank. The walls have a height of about 30 to 40 cm and an adjacent wildflower strip or field margin. The width of the installations can vary greatly: between 1.5 and 5 meters are common.
The primary goal of maintenance measures is to suppress weeds. In the first year, the Beetle Bank can be mowed twice to promote grass growth. An important point is to remove problematic weeds such as creeping thistles (Cirsium arvense) early, before they produce seeds and spread. This means that mowing should take place before seed formation. The cutting height should be adjusted to the seed mixtures used. For perennial flowering plants, for example, the height should be at least 15 cm to avoid damaging the plants.
From the second year, regular mowing is often no longer necessary. The prerequisite: well-established grasses and few weeds. However, a maintenance cut can be carried out every two to three years to avoid bushing. Important: Cutting against bushing should preferably not take place before August 1st to protect nesting birds.
Avoid drift onto the affected areas as much as possible, and after creating the Beetle Bank, no further soil cultivation should take place. The wall should also not be used to turn the tractor.
Depending on the state and support, any fertilization or weed control, including pesticides and growth regulators, is prohibited. Interested parties should inquire in advance with their local authority about the extent to which the measure is supported and what conditions must be met. In Bavaria, for example, the Beetle Bank is supported as part of the KULAP. To obtain reliable information about the support and requirements, the weekly magazine for Bavaria has inquired at the agricultural institutes in Triesdorf: Beetle Banks are supported through the KULAP K51 Biodiversity Strips with €800/ha.
