Common name: Scarab beetles, dung beetles
Number of species: 88
Size Range: 2-20mm
Description:
The largest family within Scarabaeoidea, Scarabaeidae has 83 British representatives in six subfamilies, and includes the chafers, scarab beetles and the majority of the dung beetles. Small to large species (3-20mm), most are powerfully built beetles with fossorial legs and some can swarm in large numbers.
Subfamily Aegialiinae has three British species, all small (4-5mm), elongate and associated with decaying vegetation in dry, sandy areas. Psammoporus sabuleti (Panzer) is a local species of sandy river banks: both Aegialia species are locally-distributed maritime beetles.
Aphodiinae is the largest subfamily with 55 species, the majority of which are dung beetles in the genus Aphodius. Built like scaled-down Geotrupidae, Aphodiinae very rarely excavate tunnels and larvae are instead found in surface dung or decaying vegetable matter. Adults generally have a smooth, black, rounded pronotum and black, brown or red striate elytra.
The subfamily Aphodiinae also includes two introduced species of Saprosites, S. mendax (Blackburn) and S. natalensis (Peringuey) which are often elevated to subfamily level as the Eupariinae. These are 3mm shining black species with strongly punctured striate elytra and red appendages, found under bark or from the burrows of Lucanidae species. Tribe Psammodiini is also often elevated to subfamily level: of these, Brindalus porcicollis (Illiger) is extinct in Britain, Pleurophorus caesus (Creutzer) and Rhyssemus germanus (L.) are known from old records, and the remaining four species – Diastichus vulneratus (Sturm), Psammodius asper (Fabricius), Tesarius caelatus (LeConte) and T. mcclayi (Cartwright) – are rare or very local. Small (2.5-4.5mm) beetles, they have obviously-ridged pronotums.
Subfamily Scarabaeinae includes nine British species, eight 4-11mm Onthophagus species and the probably-extinct Copris lunaris L. (14-20mm). Primarily associated with dung, these species can also be found in carrion and rotting fungi. They are black beetles, some species with paler elytra, and dig vertical burrows beneath dung.
The subfamily Melolonthinae are chafers, rather than dung beetles, and larvae of the eight British species can be found feeding on plant roots while the large brown adults fly strongly, often coming to light. Polyphylla fullo (L.) is included on the British list but is thought to be largely adventitious. The large brown chafer Melolontha melolontha (L.) (cockchafer or maybug) is a member of this subfamily and can occasionally swarm in large numbers.
Rutelinae is a small subfamily, with just two British representatives. Both have a bottle-green metallic pronotum and brown elytra: Anomala dubia (Scopoli) is a local, coastal species mainly found in the south, while Phyllopertha horticola (L.) is widespread and often common, particularly in the south.
Cetoniinae (including the tribe Trichiini, often promoted to family level) has six British members, mostly bright metallic species although Trichius fasciatus (L.) is a black and yellow bee mimic. None are particularly common: the most widespread is probably the rose chafer Cetonia aurata (L.) which can be found visiting flowers, particularly in southern England.
The family Scarabaeidae, as currently defined, consists of over 35,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change. Several groups formerly treated as subfamilies have been elevated to family rank (e.g., Bolboceratidae, Geotrupidae, Glaresidae, Glaphyridae, Hybosoridae, Ochodaeidae, and Pleocomidae), and some reduced to lower ranks. The subfamilies listed in this article are in accordance with those in Catalog of Life (2023).
The scarab beetles (Scarabaeidae) are a very speciose family with more than 28,000 species worldwide. From Germany 160 species have been recorded. The majority of the small to large beetles occurs in the tropic areas. The species live on flowers, shrubs and trees, others feed on dung. The large and colorful tropical species are favored by many beetle breeding enthusiasts.
Description
Scarabs are stout-bodied beetles, many with bright metallic colours, measuring between 1.5 and 160 millimetres (0.059 and 6.3 in). They have distinctive, clubbed antennae composed of plates called lamellae that can be compressed into a ball or fanned out like leaves to sense odours. Many species are fossorial, with legs adapted for digging. In some groups males (and sometimes females) have prominent horns on the head and/or pronotum to fight over mates or resources. The largest fossil scarabaeid was Oryctoantiquus borealis with a length of 50 millimetres (2.0 in).
The C-shaped larvae, called grubs, are pale yellow or white. Most adult beetles are nocturnal, although the flower chafers (Cetoniinae) and many leaf chafers (Rutelinae) are active during the day. The grubs mostly live underground or under debris, so are not exposed to sunlight. Many scarabs are scavengers that recycle dung, carrion, or decaying plant material. Others, such as the Japanese beetle, are plant-eaters, wreaking havoc on various crops and vegetation.
Some of the well-known beetles from the Scarabaeidae are Japanese beetles, dung beetles, June beetles, rose chafers (Australian, European, and North American), rhinoceros beetles, Hercules beetles and Goliath beetles.
Several members of this family have structurally coloured shells which act as left-handed circular polarisers; this was the first-discovered example of circular polarization in nature.
Dung beetles do just what their name suggests: they use the manure, or dung, of other animals in some unique ways! These interesting insects fly around in search of manure deposits, or pats, from herbivores like cows and elephants. Dung beetles come in a variety of colors, from dull and glossy black to metallic green and red. Ancient Egyptians thought very highly of the dung beetle, also known as the scarab (from their taxonomic family name, Scarabaeidae). They believed the dung beetle kept the Earth revolving like a giant ball of dung, linking the insect to Khepri, the Egyptian god of the rising sun.
Dung beetles have impressive “weapons,” some with a large, hornlike structure on the head or thorax that males use for fighting. They have spurs on their back legs that help them roll the dung balls, and their strong front legs are good for fighting as well as digging. Most dung beetles are strong fliers, with long flight wings folded under hardened outer wings (elytra), and can travel several miles in search of the perfect dung pat. With specialized antennae, they can catch a whiff of dung from the air.
HABITAT AND DIET
Dung beetles are found on all continents except Antarctica and live in farmland, forest, grassland, prairie, and desert habitats.
Most dung beetles use the manure of herbivores, which do not digest their food very well. Their dung contains half-digested grass and a smelly liquid. It is this liquid that the adult beetles feed on. Some of them have specialized mouthparts designed to suck out this nutritious soup, which is full of microorganisms that the beetles can digest. A few species feast on the dung of carnivores, while others skip the doo-doo and instead eat mushrooms, carrion, and decaying leaves and fruits.
Timing is everything for dung beetles. If the dung has been sitting long enough to dry out, the beetles can’t suck out the nutrition they need. One study in South Africa found that dung beetles laid more eggs during the rainy season when dung pats contain more moisture.
FAMILY LIFE
Scientists group dung beetles by the way the beetles make a living: rollers, tunnelers, and dwellers. Rollers form a bit of dung into a ball, roll it away, and bury it. The balls they make are either used by the female to lay her eggs in (called a brood ball) or as food for the adults to eat. Tunnelers land on a manure pat and simply dig down into the pat, burying a portion of the dung. Dwellers are content with staying on top of the dung pat to lay their eggs and raise the young.
After a chance encounter at a dung pat, male and female rollers establish a pair bond. The male offers the female a giant-sized brood ball. If she accepts it, they roll it away together or the female rides on top of the ball. They must watch out, though, as other beetles may try to steal their ball!
The new pair finds a soft place to bury the ball before mating. The male then leaves to find more partners. The female stays to make another brood ball or two and lays a single egg in each. She then coats and seals the ball with a mixture of dung, saliva, and her own feces and stows it underground. Some dung beetle mothers stay with the ball for two months, cleaning the larvae (called grubs) that hatch and removing their feces.
Tunnelers dive into a cow pile and tunnel straight down to set up the family home. Storing the dung underground keeps it fresh and protects the developing grubs from predators and parasites. The female sorts through dung and arranges it throughout the tunnel. The male’s job is to bring home the doo-doo. One or both of the parents stay with the larvae until they mature, which can take up to four months. This level of parental care is unusual in the insect world.
Dwellers are on top of the world—or at least the dung heap. The female lays her eggs on top of manure piles, and the entire development from egg to adult takes place inside the dung pat. Dwellers are smaller than tunnelers and rollers, and they seem to like cow patties best for raising a family. The adults can be found in fresh, moist droppings, while the larvae are slowly growing in dung that is drying out.
