Guide to families

For a simple picture guide to the British families click HERE.

With more than 4000 species in about 1300 genera and nearly 100 families our fauna can be very difficult for the beginner to comprehend, especially so because of the way evolution works, which means that species from distantly-related families may look superficially similar because of morphological convergence, and similarly species within a family may look very different because of divergence. In such cases the answers lie in the fine detail. The majority of our species are included within a dozen or so large and distinctive families and so there will be plenty of stuff to keep the beginner occupied but unusual specimens will soon appear that will be more difficult to assign, and this is the point of what follows. Most of this page is devoted to assigning specimens to their correct families but the method we use is intended to be simple and user-friendly; it relies heavily on pictures (a resource that hasn’t always been available in the past) because visual recognition is what our human brains are very good at, but in each case we include a few simple notes of guidance which should be taken very seriously as they are chosen to overcome some of the problems of convergence and divergence.

It should be realized from the beginning that a basic familiarity with the terminology of beetle morphology is absolutely essential and we have tried to keep this simple. For the purpose of identification, where a critical visual awareness is the most important aspect (at least to the family level), this is all that is required and to facilitate this we have included a few diagrams that will provide all that is needed to use this page. Insect morphology is a vast and daunting subject that is mostly irrelevant to the study of beetles at this level but it really should be understood that in order to understand beetle evolution it is vital to understand this in fine detail- see the notes at the end of this article (actually I believe that the only way to really understand beetle evolution is by studying their molecular biology but so many people disagree with this that it will not be mentioned again, at least not here). The obvious step is to make sure that sufficient pictures are available to make the user of a guide to families confident that they have not mistaken something for something else. In truth this cannot be done without picturing at least all the genera, but the number of pictures can be drastically reduced by including a few words of guidance, and this is how our rather unorthodox guide to families will work.

Diagram 1.png
Diagram 2.png

Basic beetle morphology (Joy, 1932)

A close look at the pictures will often suffice, the comments should help, and the family links will give plenty of examples and advice. In most cases the following list can be inspected very quickly as many of the species included are so very distinctive, this should be at least as quick as using a key and should provide a confident elimination or match. Great care should be taken to measure the length of a specimen as this can sometimes eliminate groups of families. At this point it should be mentioned that experienced coleopterists know what features to look for, they also have a very critical eye for detail and the ability to assess things like the number of tarsal segments when these might seem confusing, these things cannot be understood without a good deal of experience and so those attempting to place specimens for the first time should be aware that a very critical eye needs to be developed, after a while many features and groups will be instinctively ignored because that’s what experience allows, but at first pay critical attention to any features mentioned. Comments in square brackets can be ignored [they are mostly for the pedantic] but may provide some insight to our fauna. Another aspect of identification must be mentioned and it is something that all experienced coleopterists understand, information about the origin of a specimen can greatly facilitate identification, if it was found in dung or at sap or on a particular plant this can suggest a species or group of species, and when sampling for a particular species this can dictate which trapping method to use or which plants to look at. Such things are for the experienced beetler and are only mentioned briefly below, on the other hand each family is linked to a page that should provide an abundance of such information as well as a much wider range of photographs of named species, in fact the majority of our species are featured and so with a little searching this site should get most specimens to at least the generic level.

MYXOPHAGA 

Minute Bog Beetles

1 species

  • 0.6-0.8mm

  • Hemispherical, dark brown or black.

  • Antennae 11-segmented with a 3-segmented club.

  • Tarsal formula 3-3-3

  • Very rare, wetland margins.

Sphaerius acaroides 1.jpg
ADEPHAGA

Whirligigs

12 species

  • 3.5-7.8mm

  • Highly modified legs, reduced antennae and horizontally-divided eyes - nothing else remotely similar.

  • Tarsal formula 5-5-5

  • Aquatic.

Gyrinus marinus 1.jpg

Crawling Water Beetles

19 species

  • 2.4-5mm

  • Short filiform antennae, punctured elytral striae. Legs long and slender.

  • [Greatly expanded hind coxal plates]

  • Tarsal formula 5-5-5

  • Aquatic.

Haliplus ruficollis 1.jpg

Burrowing Water Beetles

2 species

  • 3.5-5mm

  • Similar to Dytiscidae but the ventral surface is flat and some middle antennal segments are enlarged.

  • Elytra with large punctures, especially in the apical half. 

  • [Hind coxae elevated medially.]

  • Tarsal formula 5-5-5

  • Aquatic.

Noterus clavicornis 2.jpg

Screech Beetles

1 species

  • 8-10mm

  • Large and prominent eyes. Body very convex ventrally.

  • Tibiae with long apical spurs.

  • Tarsal formula 5-5-5

  • Aquatic.

Hygrobia hermanni 6.png

Diving Beetles

120 species approx.

  • 1.9-38mm

  • Shape varies from broadly-oval to elongate-oval but always more-or-less boat-shaped, convex above and below.

  • Eyes at most only moderately convex, antennae filiform.

  • Tarsal formula 5-5-5

  • Aquatic, but many species attracted to light.

Dytiscus marginalis 3.jpg
Ilybius ater 2a.jpg
Rhantus suturalis 1.jpg
Hyphydrus ovatus 2.jpg

Ground Beetles

360 species approx.

  • 1.5-35mm

  • At least some sensory setae on the body.

  • Antennae filiform.

  • Some colourful and/or metallic species.

  • [Prosternum with distinct notopleural sutures, hind coxae dividing the first visible sternite and not expanded laterally to meet the elytral epipleura, hind trochanters extending some way along the hind margin of the femora.]

  • Tarsal formula 5-5-5, rarely with bilobed segments.

  • Most habitats, rarely aquatic.

Carabus granulatus 1.jpg
Cicindela campestris 3.jpg
Amara aenea 4.jpg
Dromius agilis 1.jpg
Bembidion quadrimaculatum.jpg
POLYPHAGA
HYDROPHILOIDEA

Grooved Water Scavenger Beetles

20 species

  • 2.1-7.1mm

  • Maxillary palps as long as antennae. Pronotum with longitudinal grooves, the innermost of which are sinuate or kinked about the middle.

  • Elytra with punctured striae, sometimes with longitudinal ridges.

  • Tarsal formula 5-5-5.

  • Mostly aquatic, some terrestrial species.

Helophorus flavipes 1.jpg

Minute Mud Beetles

1 species

  • 1.5-2.0 mm

  • Unique appearance. Head hidden from above, 9-segmented antennae with a pubescent 3-segmented club.

  • Large elytral punctures.

  • Outer margin of front tibiae angled.

  • Tarsal formula 4-4-4

  • Wetland margins.

Georissus crenulatus 2.jpg

Hydrochid Beetles

7 species

  • 2.1-4.7 mm

  • Eyes convex and very prominent, no longitudinal grooves to the pronotum, elytra with punctured striae.

  • Palps not greatly longer than the antennae, antennal club 3-segmented.

  • Tarsal formula 5-5-5

  • Aquatic and wetland margins.

Hydrochus angustatus 2.jpg

Filter-Feeding Water Beetles

1 species

  • 5-7mm

  • Anterior margin of head emarginate. Very transverse pronotum. Palps longer than the antennae. Tibiae without long apical spurs.

  • Tarsal formula 5-5-5

  • Aquatic and wetland margins.

  • Thought to be extinct in the UK.

Spercheus emarginatus 1.jpg

Water Scavenger Beetles

74 species

  • 1.2-70mm

  • Elongate - oval and continuous in outline, convex above and flat below. Antennae inserted under the side of the head, almost always 9-segmented, club with 3 segments. Palps longer than the antennae (or very nearly so in some smaller species).

  • Tarsal formula usually 5-5-5; a few aquatic species are dimorphic, the males having 4-segmented front tarsi.

  • Aquatic, dung and compost, regularly at light.

Hydrophilus piceus 2.jpg
Enochrus testaceus 3.jpg
Cercyon unipunctatus 1.jpg
Sphaeridium lunatum 2.jpg

False Clown Beetles

1 species

  • 5.5-6.5 mm

  • Antennae not geniculate, with a 3-segmented club, all the segments clearly visible. Front tibiae with fine spines but without teeth and lacking tarsal grooves. Elytra leaving one abdominal tergite exposed, each with nine distinct rows of punctures.

  • Tarsal formula 5-5-5

  • Northern conifer forests.

Sphaerites glabratus 1b.jpg

Clown Beetles

53 species

  • 0.8-11.0 mm

  • Antennae geniculate and clubbed. Front tibiae with tarsal grooves and usually dentate externally, elytra usually leaving two abdominal tergites exposed. Elytra very variable but never with nine rows of punctures.

  • Most genera are distinctive but experience will be needed with some of the small specimens, all of which are pictured on the family page.

  • Tarsal formula 5-5-5

  • Carrion, dung, decaying wood and vegetation.

Hister illigeri 1.jpg
Paromalus flavicornis 1lb.jpg
Haeterius ferrugineus 1.jpg
Hololepta plana 1.jpg
STAPHYLINOIDEA

Moss Beetles

33 species

  • 1.0-2.8 mm

  • Palps at least as long as the antennae, in most cases very much longer. Antennal club 5-segmented.

  • Tarsal formula 5-5-5, often appearing 4-segmented.

  • Aquatic and wetland margins.

Hydraena riparia 1.jpg
Limnebius truncatellus 1.jpg
Ochthebius viridis.jpg

Feather-Winged Beetles

76 species

  • 0.5-1.3 mm

  • Tiny species, antennae distinctive; one or (usually) two large basal segments, others  with long fine setae, club long and loose, insertions separated by at least the length of the two basal segments.

  • Tarsal formula variable, 2- or 3-segmented.

  • Decaying wood and vegetation.

ptilium_horioni_1.jpg
acrotrichis_brevipennis_1c.jpg

Fungus Beetles

94 species

  • 1.3-6.0 mm

  • Most are elongate - oval and discontinuous in outline, some have a distinct occipital ridge, in many the base of the elytra is slightly narrower than the pronotal base. Most have a distinctive antennal club, five-segmented with the second segment smaller than the first and third (some Cucujidae also have this form of antennal club but are otherwise very different.)

  • Agathidium have a normal three segmented club but the species are globose and distinctive, Colon have a four-segmented club but are otherwise distinctive, Choleva and Catopidius have almost filiform antennae but the occipital ridge is obvious, Parabathyscia and Leptinus are eyeless, and Platypsyllus is uniquely weird.

  • Tarsal formula variable, 3-3-3 to 5-5-5.

  • Carrion and decaying vegetation.

Leiodes calcarata 1a.jpg
Anisotoma humeralis 1.jpg
colon_serripes_1b.jpg
Choleva oblonga 1.jpg

Carrion Beetles

21 species

  • 9-30 mm

  • Either 12-30mm with elytra truncate, exposing the abdominal apex (Nicrophorinae) OR 9-17mm, head very narrow compared with the pronotum, elytra without punctured striae and front tibiae characteristic (Silphinae).

  • Tarsal formula 5-5-5.

  • Carrion and decaying fungi etc., often at light.

Silpha obscura 1.jpg
Nicrophorus vespilloides 1.jpg

Rove Beetles

1100 species approx.

  • 0.9-30 mm

  • Most are elongate and have short elytra which leave the abdomen substantially exposed, Scydmaeninae, and to a lesser degree Scaphidiinae, are the exceptions but they are otherwise very distinctive.

  • Most morphological features vary between and within subfamilies but the various forms will soon become familiar.

  • Certain Omaliinae have two ocelli and in Metopsiinae there is a single ocellus.

  • Pselaphinae have clubbed antennae and some have hugely-developed palps.

  • In most scydmaeninae the elytra cover the abdomen, they are small, at most 2.1 mm, and generally distinct; all have 5-segmented tarsi, all coxae are distinctly separated and most have small pits along the base of the pronotum and a small terminal maxillary palpomere.

  • Tarsi various but never pseudotetramerous on all legs.

  • All habitats, many on wetland margins but no true aquatic species.

Staphylinus caesareus 1.jpg
Omalium laeviusculum 1.jpg
Tachyporus hypnorum 2.jpg
Oxytelus laqueatus 1.jpg
Scydmaenus tarsatus 3.jpg
Stenus bimaculatus 3.jpg
SCARABAEOIDEA

Dor Beetles

8 species

  • 7-26 mm

  • Very distinctive; mandibles projecting, eyes divided by a horizontal bar, antennae 11-segmented. Elytra very convex and covering abdomen.

  • Males of some species have horns.

  • Tarsal formula 5-5-5.

  • Dung pasture and woodland, often at light.

Geotrupes stercorarius 1A.jpg
Odonteus armiger.jpg

Skin Beetles

3 species

  • 5-12mm

  • Antennae 10-segmented with a 3-segmented, internally-expanded club. Pronotal and elytral sculpture distinctive. mm

  • 5 visible sternites, epipleura wide to elytral apex.

  • Tarsal formula 5-5-5.

  • Bird nests, bones and carrion, sometimes at light.

Trox scaber 2.jpg