Scarab Beetles (Scarabaeidae)
SCARABAEIDAE – MORPHOLOGY, ECOLOGY, AND GLOBAL DISTRIBUTION
The family Scarabaeidae (from Latin scarabaeus, “beetle,” historically linked to the sacred scarabs of ancient Egypt) represents one of the largest beetle families, encompassing over 30,000 described species worldwide. Europe harbors approximately 1,000 species, with around 150 species recorded in the Czech Republic. Adult body sizes range from 5 to 60 mm, typically robust and oval, with hard, glossy elytra exhibiting metallic hues of green, bronze, or red. Characteristic lamellate antennae (antennal clubs with articulating lamellae capable of forming a compact sphere) facilitate acute olfactory perception.
Forelegs are broadened and fossorial, specialized for digging, while the hind legs of certain dung-rolling species are powerful, adapted for transporting dung balls. The head is robust with strong mandibles. Adult feeding ecology is diverse: coprophagous (dung-feeding), nectarivorous, or folivorous. Larvae, termed grubs or scarabaeid larvae, are C-shaped, whitish, thick-bodied, with three-segmented thoracic legs. Wikipedia
DISTRIBUTION AND REPRESENTATIVE SPECIES IN THE CZECH REPUBLIC
In the Czech fauna, the dominant subfamilies include Scarabaeinae (dung beetles) such as Polyphylla fullo (oak chafer), Cetoniinae (flower chafers) like Cetonia aurata and Potosia cuprea, and Rutelinae (leaf chafers) such as Amphimallon solstitiale. The sacred scarab (Scarabaeus sacer) is Mediterranean and absent in the Czech Republic, but analogous species like Copris lunaris are present in pastures. Globally, scarab beetles exhibit a Mesozoic origin and have colonized tropical, subtropical, and temperate regions, with many lineages adapting to arid or semiarid environments. Numerous species are threatened according to regional Red Lists due to pasture loss, deforestation, and land-use intensification.
ECOLOGY AND HABITAT PREFERENCES
Scarab beetles occupy a range of terrestrial habitats, including pastures, forests, meadows, orchards, and agricultural landscapes. Adults contribute to nutrient cycling by decomposing dung, leaf litter, or pollen. Females of coprophagous species construct dung balls to provision developing larvae, which enhances soil aeration and fertility. Most scarabs are nocturnal, although flower chafers and leaf chafers are diurnally active. Larvae develop in soil or organic substrates for 1–3 years, feeding on roots or decaying matter.
LARVAL DEVELOPMENT (GRUBS)
Scarabaeid larvae are thick-bodied, C-shaped, and white to yellow, with brownish heads. They may reach up to 60 mm in length. Grubs feed on plant roots, dung, or humic substrates, progressing through three larval instars over 1–4 years. While occasionally pests in turf or crops, they contribute significantly to humus formation and soil structure. Pupation occurs in an earthen chamber, culminating in adult emergence in spring or summer.
REPRODUCTION AND LIFE CYCLE
Females deposit eggs in dung balls or soil depressions from spring through summer. Eggs hatch in 1–2 weeks, with larval development lasting 1–3 years depending on species and environmental conditions. Adults overwinter in soil and emerge in spring, completing a life cycle of 1–4 years. Some iconic species, such as the sacred scarab, exhibit celestial orientation behavior for navigation, using the Milky Way as a reference during dung ball rolling.
ECOLOGICAL SIGNIFICANCE AND CONSERVATION
Scarab beetles are keystone species in terrestrial ecosystems, functioning as nutrient recyclers, soil enhancers, and pollinators. However, larval grubs can cause localized damage to turfgrass or crops. Threatened species require habitat protection through the maintenance of pastures, extensive grazing systems, and retention of deadwood within Natura 2000 sites. Conservation strategies emphasize habitat restoration, population monitoring, and maintenance of ecological connectivity to preserve global scarabaeid biodiversity. Globally, scarab beetles serve as model organisms for studies of ecological engineering, nutrient cycling, and coevolution with vertebrates, particularly in dung beetle-vertebrate mutualisms.