Scarab Beetles (Family Scarabaeidae): Fauna in the UK
The Scarab beetles of the family Scarabaeidae are a diverse and ecologically significant group of beetles, many of which are associated with dung, decaying matter, and plant roots. Though they are more abundant in tropical and subtropical regions, the UK hosts around 30 species, which play essential roles in nutrient recycling, soil aeration, and the maintenance of local ecosystems. This essay explores the physical characteristics, habitat preferences, ecological roles, and conservation challenges associated with scarab beetles in the UK.
Physical Characteristics and Identification
Scarab beetles in the UK range widely in size, colour, and shape, though many exhibit the robust and rounded body shape characteristic of scarabs worldwide. Some are brightly coloured, while others have a more subdued appearance in shades of brown, black, or metallic green. One of their distinguishing features is the presence of clubbed antennae with small, leaf-like plates, known as lamellae, that can be opened and closed to sense odours. Many scarabs also have strong, spiny legs adapted for digging, an essential feature for beetles that burrow into the ground to lay their eggs.
Habitat and Distribution
UK scarab beetles occupy various habitats, from grasslands and woodlands to agricultural fields and gardens. Their habitat preferences are closely tied to their diet and reproductive needs:
- Dung beetles, such as Geotrupes stercorarius and Aphodius fossor, are commonly found in pastures, meadows, and fields where they have access to livestock dung. These beetles play a crucial role in recycling nutrients from dung back into the soil.
- Chafer beetles, such as the Cockchafer (Melolontha melolontha) and the Garden Chafer (Phyllopertha horticola), are associated with grasslands and gardens, where their larvae feed on plant roots.
- Wood-associated scarabs, like the Rhinoceros Beetle (Sinodendron cylindricum), inhabit woodlands and prefer decaying wood for larval development.
A list of some notable Scarab beetles (family Scarabaeidae) found in the UK, along with short descriptions of each:
Common Dung Beetle (Geotrupes stercorarius)
A large, metallic green or black beetle that plays a critical role in recycling animal dung. Common in pastures and fields, it buries dung to lay its eggs.
Lesser Dung Beetle (Aphodius fossor)
A small, dark brown beetle often seen in cattle pastures. It feeds on dung and is vital for nutrient cycling in agricultural areas.
Minotaur Beetle (Typhaeus typhoeus)
Known for its three large horns on the male’s thorax, this black beetle buries dung in sandy soil, mainly found on heathlands and moorlands.
Rhinoceros Beetle (Sinodendron cylindricum)
A small, black or brown beetle with a distinctive horn-like projection on its head. Found in decaying wood, particularly in ancient woodlands.
Cockchafer (Melolontha melolontha)
Also known as the May bug, it is a large, brown beetle with distinctive fan-like antennae. Its larvae, known as “white grubs,” feed on plant roots and are found in grasslands and gardens.
Garden Chafer (Phyllopertha horticola)
A small beetle with a metallic green head and bronze body. Common in gardens and grasslands, its larvae feed on grass roots and can sometimes damage lawns.
Summer Chafer (Amphimallon solstitiale)
A medium-sized, brown beetle active in early summer. Its larvae develop in soil, feeding on roots of grasses and plants, found in gardens and grasslands.
Violet Ground Beetle (Carabus violaceus)
[Note: This beetle is often confused with scarabs due to its robust shape but actually belongs to a different family, Carabidae]
Large and metallic violet or black, this ground beetle is common in woodlands and gardens. It feeds on small invertebrates and is beneficial for pest control.
Sexton Beetle (Nicrophorus vespilloides)
[Note: Often mistaken for scarabs but actually belongs to the family Silphidae]
Black and orange markings, it buries small carcasses for its larvae, found in woodlands and fields. Plays a role in decomposition but is not a true scarab.
Welsh Chafer (Hoplia philanthus)
A small, bronze-colored beetle often found in grasslands and sandy soils. Active in summer, its larvae feed on plant roots.
These scarab beetles are an essential part of UK ecosystems, particularly those that help decompose organic matter, recycle nutrients, and maintain soil health. Their habitats range from woodlands to grasslands, and while some may be considered pests, man
The distribution of scarab beetles in the UK reflects both environmental factors and human influences. While grasslands and pastures are common habitats for dung-feeding scarabs, urban gardens and agricultural land have provided habitats for species like the garden chafer, which sometimes becomes a garden pest.
Life Cycle and Behaviour
Scarab beetles undergo complete metamorphosis, transitioning from egg to larva (often called a grub), to pupa, and finally to adult. The larvae are generally thick, C-shaped, and live within the soil or decaying organic matter. The diet and behaviour of scarab larvae vary significantly by species:
- Dung beetle larvae feed on decomposing organic matter in dung, where they gain essential nutrients for growth.
- Chafer beetle larvae are root feeders and can sometimes cause damage to grasses, crops, and garden plants, as they feed on plant roots.
- Wood-boring larvae of scarabs like the rhinoceros beetle consume decaying wood, aiding in the breakdown of dead trees and wood matter.
After the larval stage, scarabs enter a pupal stage, during which they transform into adults. The adults of many scarab species are short-lived, primarily focused on reproduction and, in some cases, feeding on flowers, leaves, or decaying matter.
Ecological Importance
Scarab beetles are vital to UK ecosystems due to their roles in nutrient cycling, soil aeration, and providing food for other wildlife. Dung beetles like Geotrupes stercorarius are among the most ecologically beneficial, as they break down animal waste and recycle nutrients back into the soil. By burying dung, these beetles also help control parasitic flies and reduce greenhouse gas emissions from livestock waste.
Chafer beetles, while sometimes considered pests due to their root-feeding larvae, are also important in their natural grassland habitats, where they contribute to the ecosystem by providing food for birds, mammals, and other insects. Wood-associated scarabs such as the rhinoceros beetle play an essential role in decomposing wood and recycling nutrients, which supports soil health and plant growth.
Conservation and Threats
The conservation of scarab beetles in the UK faces several challenges, primarily related to habitat loss, agricultural practices, and pesticide use. Habitat loss due to urbanization, deforestation, and the intensification of agriculture has reduced available habitats for many scarab species, particularly those dependent on grasslands, woodlands, and pastures.
Modern agricultural practices, including the use of pesticides and chemical fertilizers, can harm scarab beetles, especially dung beetles, which rely on dung from livestock for food and reproduction. The widespread use of antiparasitic drugs in livestock, such as ivermectin, can make dung toxic to beetles and has been linked to declines in dung beetle populations. Climate change also presents a threat, as changes in temperature and rainfall patterns can disrupt the habitats and life cycles of scarab beetles.
Despite these challenges, efforts are being made to conserve scarab beetles and their habitats. Farmers are increasingly encouraged to adopt wildlife-friendly practices, such as reducing pesticide use and maintaining field margins, which can support beetle populations. In addition, programs that promote sustainable livestock management help maintain healthier populations of dung beetles, benefiting both agriculture and biodiversity.
Conclusion
Scarab beetles, though less numerous in species variety in the UK than in tropical regions, are an ecologically vital group. Their roles in nutrient recycling, soil health, and supporting food webs underscore their importance in UK ecosystems. While some, like the garden chafer, may be seen as pests, most scarabs contribute positively to the environment. Conservation efforts that address habitat preservation, reduce pesticide use, and promote sustainable farming practices are essential for maintaining scarab beetle populations in the UK. Through these efforts, scarab beetles can continue to thrive, supporting soil health and biodiversity for future generations.