Common name: Dor beetles
Number of species: 8
Size Range: 11-26mm
Description:
The Geotrupidae have eight British representatives, seven in the subfamily Geotrupinae and one species, Odonteus armiger (Scopoli) in subfamily Bolbatocerinae, often raised to family level. This species is thought to feed on hypogeal (underground) fungi and is found mostly in the south and southeast, here it is often caught at light. Males have prominent thoracic horns.
The Geotrupinae are large black heavily-built beetles (10-26mm), often with green or blue metallic reflections. Like O. armiger, they are strong fliers and often come to light. The minotaur beetle Typhaeus typhoeus (L.) is our only member of the ‘roller’ guild of dung beetles: males have three large thoracic horns. Both sexes can occasionally be seen rolling rabbit droppings towards their deep (1-1.5m) burrows, but can be more often located by the spoil heaps their tunnelling leaves in open sandy areas. The other species excavate shorter (5-60cm) burrows beneath or directly beside dung.
UPTURNED DOR BEETLES
There are around 150 species of dung beetles in the world, with the UK home to roughly 60 species. The majority of our dung beetle species are not the ball rolling varieties that dung beetles are most famous for, but are the dwelling types living within dung piles, or the tunnelling varieties that live deep in the soil. Of course you can come across some beetles rolling very small balls of dung, however it’s not a common sight within this country.
While wandering the woods around Armathwaite recently, I kept coming across upturned Dor Beetles (Geotrupes stercorarius) struggling to get back on their feet, their beautiful violet undersides flashing in the sunlight. After trying to rescue the first couple of beetles, I realised that no matter how many times I got them onto their legs they always seemed to end up on their backs again. It intrigued me why we see so many upturned Dor Beetles scattered on paths in the late summer, so I did a little ‘digging’ myself…
Normally when a Dor Beetle has ended up on its back it will use its legs to build momentum and rock itself over. This works just fine most of the time, however when this species reaches the end of its life cycle, individuals lose their rocking ability due to their failing nervous systems, preventing them the ability to coordinate their legs. This results in countless helpless beetles flailing their legs and violet undersides in the air a the end of the summer months, most often with intrigued people hovering over them wondering what on earth is going on.
Dor Beetles – Geotrupidae
The Geotrupidae family is composed of eight species which are divided into five Genera. These are Anoplotrupes, Geotrupes, Odonteus, Trypocopris and Typhaeus.
One species, Odonteus armiger feeds on fungi, the others feed on dung. These excavate vertical burrows directly below a dung pile and drag a small portion of dung down into a brood chamber in which the eggs are laid.The excavated soil and tunnel holes, which can measure up to 20mm in diameter, can often be seen underneath or next to dung piles. Sometimes they are referred to as Dor beetles, Lousy Watchmen or Dumbledors.
Geotrupidae (from Greek γῆ (gē), earth, and τρῡπητής (trȳpētēs), borer) is a family of beetles in the order Coleoptera. They are commonly called earth-boring dung beetles or dor beetles.[1] Most excavate burrows in which to lay their eggs. They are typically detritivores, provisioning their nests with leaf litter (often moldy), but are occasionally coprophagous, similar to dung beetles. The eggs are laid in or upon the provision mass and buried, and the developing larvae feed upon the provisions. The burrows of some species can exceed 2 metres in depth.
A few species communicate by stridulation (rubbing body parts together to make sounds).
Classification
They were originally [when?] classified as the subfamily Geotrupinae in the family Scarabaeidae before being elevated to a family. Traditionally the family Bolboceratidae was included (as the subfamily Bolboceratinae) on the basis of the number of antenna segments, but examination of a different set of characteristics prompted Scholtz & Browne (1995) to elevate Bolboceratidae to a family, a result supported by recent phylogenetic research.
The family has more than 600 species in about 30 genera in two subfamilies; recent [when?] phylogenetic studies indicate that Taurocerastinae is not related to Geotrupinae, and is instead more closely related to Lucanidae and Diphyllostomatidae.
