Common name: Ground beetles
Number of species: 374
Size Range: 2-30mm
Tarsi: 5-5-5.
Ground beetles are a large, cosmopolitan family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it is one of the 10 most species-rich animal families. They belong to the Adephaga. Members of the family are primarily carnivorous, but some members are herbivorous or omnivorous.
Description:
A large family (362 species on the 2012 edition of the British list) which includes some of the largest and showiest British beetles, reaching 30mm long. With such a large group – there are more carabids on the British list than there are breeding bird species – carabids can be found almost anywhere, but riparian and coastal habitats seem particularly species-rich.
Traditionally sub-divided into many subfamilies, the 2012 British list recognises only four: Cincindelidae (five species of tiger beetle), Brachininae (two species of bombardier beetles), Omophroninae (one species), and Carabinae (the ‘traditional’ ground beetles, 354 species).
The one British species of Omophroninae is Omophron limbatum (Fabricius), a semi-aquatic species found burrowing in sand around flooded sand-pits. Rather more rounded than most carabids, the species is a straw-yellow colour with darker patterning, reminiscent of a 14-spot ladybird (Propylea quattuordecimpunctata (L.)).
The two species of Brachininae, the bombardier beetle Brachinus crepitans (L.) and the streaked bombardier beetle B. sclopeta Fabricius, both of which are famous for their ability to expel a 100°C jet of chemicals from the anus to deter predators. This is produced when hydroquinone and hydrogen peroxide from separate glands are mixed, and the resulting explosion can be heard as an audible crackle. Both species are 6-10mm long and have an orange head and thorax, and blue-green elytra, B. sclopeta with an orange streak down the elytral suture. Brachinus crepitans is found mainly on calcareous grasslands, arable field margins and chalk quarries, with most modern records from coastal areas, while B. sclopeta has always been rare and is now only found on a handful of brownfield sites in London.
The Cincindelidae were previously raised to family level, but have been regarded as a subfamily within Carabidae since 1974. The five British species are relatively large (8-19mm) and brightly-coloured. Diurnal predators, they can be found running at speed in open, dry situations primarily in spring and early summer. Larvae lurk at the bottom of vertical tunnels which act as pitfall traps for small invertebrates.
Carabinae is by far the largest subfamily, and includes both the largest and most frequently encountered species, such as Carabus violaceus L., Carabus problematicus Herbst, Nebria brevicollis (Fabricius), and Pterostichus madidus (Fabricius). Most are ground-dwelling predators or scavengers, but others burrow in the soil (tribes Broscinae and Scaritinae), forage on tree branches (various Dromiini), or in the intertidal zone (Aepus marinus (Strom) & Aepus robinii (Laboulbene)). Most are largely nocturnal, but several large-eyed species are diurnal (Elaphrus and Notiophilus spp. in particular)
Many species have pronounced habitat preferences, and coastal habitats, upland moorland, woodland and riparian shingle all have distinct faunas. Several come to light, particularly Ophonus spp.
The ground beetles (Carabidae) are a very large family with more than 40,000 scientifically described species worldwide. More than 550 species are recorded from Germany. The majority of them are land-dwellers, but a few species are aquatic hunters. Most of the species are nocturnal and carnivorous and prey on invertebrates and their larvae. Large species (e.g. genus Carabus) can also overpower smaller mollusks, like worms or slugs. Some species are herbivorous and feed on grass seeds with high contents of fats and starch. They can be found from the lowland up to alpine levels and in many different habitats, from wet to xerothermic. They have also occupied special ecological niches: Some species live under the bark of trees (corticolous), on trees and shrubs (arboreal), in caves (cavernicolous) or subterraneous (hypogaeic).
What is the most common ground beetle?
They are medium-to large sized ground beetles (~ 12-28 mm). The most common species (although invasive from Europe) in North America, P. melanarius (shown above), is a nondescript black color, but other members have more of a metallic sheen (Lindroth 1969).
What are the characteristics of a ground beetle?
Ground beetles are recognized by their long legs and shiny black or brown elytra (wing covers), which are decorated with ridges and may be fused together along the midline. In many species the hind wings are reduced or absent. Ground beetles prefer moist cool areas and usually run rather than fly when disturbed.
