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More about our AI transparencyDiscover why dead plant stems and deadwood are essential for wild bees, and how to effectively support above-ground nesting solitary bees in your garden.
A tidy garden in late autumn may look neat to many, but it deprives numerous insects of their very livelihood. Whilst roughly 70 to 75 per cent of native wild bee species nest in the ground, another portion of our more than 600 wild bee species relies on above-ground cavities. Withered, pith-filled, or hollow plant stems, as well as abandoned beetle boreholes in deadwood, serve as indispensable nesting and overwintering sites. Anyone who cuts perennials down to ground level ahead of winter inadvertently destroys eggs, larvae, or pupae. By leaving dead plant matter standing well into spring and preserving deadwood structures, a garden can be transformed into an effective wildlife sanctuary without any extra effort.
When the flowering season draws to a close in autumn, herbaceous borders change their appearance. Green leaves turn brown, seed heads dry out, and rigid stems remain behind. In conventional gardening, this state is frequently regarded as the signal for a thorough autumn cut-back. From an ecological perspective, however, this marks the beginning of a decisive phase for the conservation of biodiversity.
What at first glance resembles rotting garden waste performs central protective and sustaining functions in natural ecosystems. For numerous insects, dried stalks and weathered branches are not clutter; they are quite simply the foundation of their reproduction. A withered perennial stem is often not dead plant tissue at all, but a densely occupied nursery for the next generation of wild pollinators.
More than 600 different wild bee species are native to Germany, as set out in the YouTube description, amongst other sources. These species exhibit a remarkable diversity in their living and nesting habits. Wild bees can be broadly differentiated by where and how they construct their brood cells.
According to specialist information provided by the platform Naturkompass, approximately 70 to 75 per cent of native wild bee species dig their nests directly into the soil. These ground nesters depend on bare, unshaded, and, above all, unmulched soil patches—such as sandy banks, erosion edges, or sparsely vegetated path joints.
The remaining species employ entirely different strategies and nest above ground. These insects do not burrow into the earth, but instead search for existing cavities above soil level. These include:
Each species imposes very specific requirements regarding the diameter, material properties, and orientation of the nesting cavity.
Above-ground nesting wild bees, such as many mason bees (Osmia), scissor bees (Chelostoma), or yellow-faced bees (Hylaeus), rear their offspring in linearly arranged brood cells. The process inside a hollow or pithy stem follows a highly precise biological pattern:
Some species display fascinating specialisations. Leafcutter bees (Megachile), for instance, use their mandibles to cut neatly tailored, semi-circular sections from living leaves. They transport these leaf fragments into the nesting tunnel and completely line their brood cells with them, as described on the information platform Naturkompass.
A widespread misconception in gardening practice is the belief that insects simply die off in autumn or retreat exclusively deep underground. For many stem-dwelling wild bees, the opposite is true: they spend the entire cold season directly within the plant stem.
From the deposited egg, a larva hatches in summer or early autumn and consumes the provisioned food cache. Depending on the species, the larva pupates before winter or remains in diapause as a prepupa (resting larva). Other species complete their metamorphosis in autumn and overwinter inside the protected cell as fully formed, cold-torpid adult insects (imagines).
If withered perennials are cut down to the ground in October or November and disposed of on the compost heap, shredded, or collected in the garden waste bin, the entire next generation of bees is destroyed. The protected chambers rot in moist compost or are mechanically crushed. Leaving dry plant parts standing is therefore one of the most effective conservation measures in a wildlife garden.
Alongside dead perennial stems, woody material plays an outstanding role in garden ecosystems. As data from the Naturkompass portal demonstrates, a deadwood corner is amongst the most structurally and biologically diverse features of all. Well over 1,500 beetle species rely on dead wood during their life cycles, as do countless fungi and lichen species.
This aspect is of direct significance for wild bees: very few bee species are physically capable of chewing their own tunnels into decaying wood. The majority of wood-dwelling wild bees rely on wood-boring beetle larvae to do the preparatory excavation. Only once the mature beetles have emerged do they leave behind boreholes in the deadwood. These prefabricated tunnels are subsequently inhabited by mason bees and related species as nesting cavities, as noted in the YouTube description.
Without dead branches, aged tree trunks, or root stumps, not only are specialised beetles lost, but the nesting sites for specialised wild bees also disappear as a consequence.
An intact nesting site remains useless if suitable foraging resources are absent within the bee's flight range. Because solitary bees often have modest operational ranges of just a few hundred metres, nesting structures and food sources must be located close together.
The educational platform Naturkompass emphasises the necessity of a continuous sequence of blooms. From the first mild spring days through to late autumn, there must be no interruptions in the supply of nectar and pollen. Nectar provides the essential flight fuel for adult bees, whilst pollen represents the protein-rich sustenance required by the developing brood within the stems.
The following overview compares the most important nesting structures in a wildlife garden based on verified ecological criteria:
| Nesting Structure | Proportion / Target Group | Typical Inhabitants | Ecological Characteristics & Maintenance |
|---|---|---|---|
| Open Soil / Sandarium | Approx. 70–75% of native wild bee species | Ground-nesting species (e.g. mining bees) | Requires unmulched, sun-exposed, sparsely vegetated open patches. |
| Hollow Plant Stems | Proportion of above-ground nesting species | Many mason bees (Osmia), scissor bees (Chelostoma) | Stems of reeds/rushes; stalks must be free of internal crushing or cracks. |
| Pith-Filled Plant Stems | Specialised stem nesters | Yellow-faced bees (Hylaeus), small carpenter bees | Stems (e.g. thistles, brambles) must remain vertical or tilted; tunnels are often excavated by the bees themselves. |
| Deadwood & Beetle Boreholes | Wood-dwelling cavity users | Various mason bees, solitary wasps | Over 1,500 beetle species create primary boreholes; wood must be allowed to weather naturally from dry to decaying. |
| Artificial Nesting Aids | Only a small fraction of total species | Few adaptable cavity nesters | Effective only with clean drill holes/reed stems; does not replace natural soil and vegetation structures. |
To assist stem-nesting wild bees effectively, expensive equipment is unnecessary; all that is needed is an altered approach to seasonal garden maintenance. The following steps can be implemented in any garden:
Leave spent and withered perennials standing throughout the winter months. The seed heads provide food for birds, whilst the stems offer protection against frost and wind, serving as winter quarters for resting insect larvae.
Do not cut back perennials until temperatures rise consistently in spring and insects have had sufficient time to emerge from their nest chambers. Depending on the region, this is often not the case until mid-April or May.
When perennial stems are shortened in spring, do not necessarily shear them down to ground level; leave stem stubs of 30 to 50 centimetres standing directly in the border. These immediately provide fresh nesting sites for the coming season.
Cut material must never be shredded immediately, as late-emerging species may still be inside. Loosely tie pithy stems together and secure them vertically to a fence or a sunny hedge. Many pith-nesting species avoid stems lying horizontally on the ground, yet readily accept upright structures.
Dead branches, log rounds, or trunk sections should not be burnt. Establish a deadwood pile in a warm, sheltered, sunny location. The solar warmth enables insect larvae to develop optimally.
Traditional "insect hotels" from garden centres or DIY builds enjoy immense popularity. Filled with reed tubes, bamboo canes, or cleanly drilled hardwood, they can be successfully used by certain mason bee species and yellow-faced bees. They also offer excellent observation opportunities in gardens or on balconies.
However, as the YouTube description objectively highlights, artificial nesting aids by no means replace nature. They cater to only a tiny fraction of the broader species spectrum. The vast majority of threatened wild bees—especially the large proportion of ground nesters, as well as specialists requiring pith-filled or vertical plant structures—gain no benefit from these boxes whatsoever.
An artificial nesting box is therefore only advantageous when embedded within a diverse habitat that offers natural structures, undisturbed soil, and native forage plants.
Occupied cavities can usually be identified by the entrance. If the stem is sealed with a plug of dried mud, resin, leaf fragments, or whitish plant hairs, a brood chamber lies behind it. Such stems must never be crushed or cut.
Most pith-dwelling bee species prefer vertical or angled stems, as stems lying on the ground quickly absorb moisture, mould, or decay. Hollow reed or bamboo tubes inside nesting boxes, on the other hand, are readily colonised even in a horizontal orientation.
Leaving dead stems standing does not mean uncontrolled neglect. You can selectively remove the seed heads of prolific self-seeders whilst leaving the sturdy, dry stems in place. Visual order can also be maintained by deliberately keeping pithy species, such as mullein, elecampane, or bramble shoots, at the margins of the border.
Because different species emerge at varying times between March and June, determining when emergence has fully completed is difficult. Leaving stem stubs permanently as structural features in the garden, or securing prunings vertically in an undisturbed spot, ensures that late bloomers are not inadvertently killed.
gartenexpedition.de/shop/) offers native seeds and accessories; however, it functions purely as a sales channel and does not constitute scientific evidence.Keywords
All species data comes from scientific sources (CC BY 4.0 / CC0). Attribution according to licence terms. Complete source overview →
Last updated: 09/09/2026. Corrections can be reported via the feedback form.