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Drilidae – Drilus flavescens

There is just a single British species of drilid, Drilus flavescens. It is a Nationally Scarce (Na) species mostly found on the chalk downs of south-east England where it preys on snails. Adult males and adult females are very different – the males can fly and have strongly pectinate antennae which probably help them to locate the females, which by contrast are large, wingless and grub-like. Males are relatively easy to see in the right habitat from about mid-May to early July, often active in the grassland ‘canopy’. By contrast, seeing a female Drilus seems to be a once-in-a-lifetime experience, and I haven’t had my one yet. In April 2012, I couldn’t even find a photo of a female Drilus on the internet! But in June 2012, Dave Gibbs sent me these photos of an adult female Drilus flavescens which he reared from a larva.

Adult female Drilus flavescens.

Adult female Drilus flavescens, another view.

To illustrate just how bizarrely different the males and females are, here’s a mating pair:

Mating Drilus flavescens, by Kate Frankland

A few years ago, Graeme Lyons sent me a photo of an extraordinary beetle larva. I eventually worked out it was a Drilus larva and since then I’ve seen quite a few photos either sent to me or posted on iSpot. They are extremely striking and highly distinctive, and clearly quite active in daytime, searching for snails to prey on. Here’s a selection of larval pictures, mostly assembled by Penny Green from Sussex naturalists: thanks to Penny, Kate Frankland, Richard Roebuck and Tim Wilton.

Drilus flavescens larva, a female (this is the same individual as the adult female featured in the top two photos).

Drilus flavescens larva, by Richard Roebuck

Drilus flavescens larva on Monacha cantiana snail, by Tim Wilton

Lionel Crawshay (1903) published a paper on the life-history of Drilus flavescens describing three years of observations on this species. It’s full of excellent information but inevitably does not answer every question, and I still don’t know whether these peculiar holes in snail shells could have been made by Drilus or not.

Drilus is mapped in Keith Alexander’s (2003) Provisional atlas of the Cantharoidea and Buprestoidea (Coleoptera) of Britain and Ireland, published by the Biological Records Centre (see their website), and is included in the Soldier Beetles, Jewel Beetles and Glow-Worms Recording Scheme run by Keith Alexander who would be pleased to receive records and happy to help with any identification problems: contact details here.

Reference

Crawshay, L. (1903). On the life history of Drilus flavescens, Rossi. Transactions of the Entomological Society of London, 51, 39 – 51 and plates I and II.

Cantharidae – Soldier Beetles

Cantharis decipiens © Alan Outen

Soldier beetles are apparently so-called because of their boldly-patterned colouration in reds, blacks, yellows and oranges, recalling the military uniforms of history. They are summer beetles, adults emerging from the pupal state in late April, May or June and dying off between June and September depending on the species. They are a familiar sight to anyone inspecting the flowers of Hogweed and other umbellifers, or generally sweeping or beating in grassland, scrub or woodland.

It is a small family of 41 species in 7 genera. The family can be divided into two. The majority of the family are medium to large, boldly coloured species in the subfamilies Cantharinae (4 genera, 24 species) and Silinae (1 species) which I think of as the true ‘soldier’ beetles. And then there are the 16 small species in Malthinus and Malthodes forming the subfamily Malthininae which are generally blackish with or without yellow markings and rarely noticed until they are on the beating tray or in the sweep-net. All are soft, flimsy and weakly chitinised beetles, especially the Malthinus and Malthodes. All the species are good fliers except for the recently discovered flightless Malthodes lobatus and whatever this species from Stodmarsh is.

Malthinus flaveolus: most of the malthinines have these bright yellow tips to the elytra.

They can be identified using
Mike Fitton’s excellent keys (from his PhD thesis), which Brian Eversham has updated. Brian has mentioned the two major changes to the British list since the keys were written:

(i)     that Malthodes brevicollis has been deleted from the British list, and
(ii)    that Malthodes lobatus has been discovered here.

There are a couple of name changes too:

(i)    Ancistronycha abdominalis is keyed out as a Cantharis but is now separated out into genus Ancistronycha;
(ii)   Cantharis bicolor is now called Cantharis cryptica.

Be warned that some of the Cantharis species in particular are exceptionally variable in colour pattern though others are highly constant. Fitton’s keys make allowance for all known variants but if you want to get to the stage where you can identify cantharids in the field, you need to be confident you know the range of variation in each species.

Keith Alexander’s Field Key to Soldier Beetles (Cantharinae and Silinae) has been in circulation since 1986. Recently, Martin Harvey has produced a revamped version which Keith has kindly allowed us to put online: download the new Field Key to Soldier Beetles (391KB PDF) here. Keith advises “this doesn’t cope with all the variation but should help people to get to grips with the species”. For those familiar with Keith’s original, Martin’s 2011 version has laid out the table in a clearer format, made some small adjustments to the wording for clarity, and added a second page summarising the habitats and status of each species (based largely on Keith’s atlas).

Be warned also that keying out female Malthodes with Fitton’s keys is probably never going to be 100% reliable. Fortunately, Malthodes are particularly easy to sex in the field, the males having much more bulging eyes and longer antennae (i.e. better developed sensory organs for tracking down females) so just pick out males for identification.

Male (top) and female (bottom) Malthodes flavoguttatus.

The other indispensable literature on the family is Keith Alexander’s (2003) Provisional atlas of the Cantharoidea and Buprestoidea (Coleoptera) of Britain and Ireland, published by the Biological Records Centre. Order from their website. It covers four smaller families too: Buprestidae (jewel beetles), Drilidae (one species: Drilus flavescens), Lycidae (net-winged beetles) and Lampyridae (glow-worms). The Lycidae, Drilus and two of the three British Lampyridae are also covered by Fitton’s keys.

Keith continues to run the Cantharoidea and Buprestoidea Recording Scheme (see here for details) and is willing to identify or check difficult specimens: he has been a great help to me by identifying specimens and offering advice. Note that the ‘Cantharoidea’ superfamily is not used in the most recent British checklist but refers to the families Cantharidae, Drilidae, Lycidae and Lampyridae, all now incorporated into the Elateroidea.

Finally, and most importantly, NEVER POOT A CANTHARID!!! They will kill and chew up every other invertebrate in your pooter, typically starting with your most exciting captures and leaving some of the dross specimens unharmed. (Do I sound bitter??). So if you are going to collect one, tube it individually or give it a sniff of ethyl acetate straight away.

Though I’ve never reared one, I frequently see what I believe to be cantharid larvae by grubbing at the soil surface. They are quite dark and have a velvety coating of hairs. There is a good paper on cantharid larvae, including a key to genera, by Mike Fitton (1975).

A presumed cantharid larva.

Thanks to Keith Alexander for commenting on a draft of this web page.

Reference

Fitton, M. (1975). The larvae of the British genera of Cantharidae (Coleoptera). J. Ent., 44: 243 – 254.

Beetle families: an overview

by Trevor James, edited by Mark G. Telfer. Latest edit: 6th March 2015.

In the most recent checklist of British and Irish beetles (Duff, 2012) the Order Coleoptera is divided into three Suborders: Myxophaga (one species only); Adephaga (comprising the predatory Ground Beetles and five water beetle families); and the Polyphaga (all the rest, divided into 16 Superfamilies). The list includes 4,072 species in 1,265 genera and 103 families (the equivalent figures for the 2008 edition were 4,034 species in 1,246 genera and 106 families). What follows is a very brief summary of the characteristics of the families.

Suborder: Myxophaga

Family: Sphaeriusidae
A small family of minute water margin beetles that feed on algae. A single British species: Sphaerius acaroides.

Suborder: Adephaga

Family: Gyrinidae
The ‘Whirligig Beetles’, named from their habit of swimming haphazardly on the surface film of water. They are specialised predators, and are especially characterised by having eyes divided across the centre so that the upper half can focus above the water, and the lower half below its surface.

Family: Haliplidae
Known as ‘Crawling Water Beetles’, this is a family of 19 species of omnivorous aquatic beetles that live in submerged vegetation.

Family: Noteridae
The ‘Burrowing Water Beetles’, mostly a tropical family, with only 2 British and Irish representatives.

Family: Hygrobiidae (name changed from Paelobiidae in Duff (2008))
There is a single species in Britain and Ireland – the aquatic ‘Screech Beetle’, named from its ability to emit a squeaking sound when handled, by rubbing the 7th abdominal segment against the ribbed underside of the elytra.

Family: Dytiscidae
The ‘Diving Beetles’ – an entirely aquatic predatory family of beetles found in all kinds of still and running water.

Family: Carabidae‘Ground Beetles’ – often fast-running, mostly predators of a wide range of other insects, although a few species feed on plant material, and some have highly specialised food sources, such as springtails or molluscs.

Suborder: Polyphaga

Superfamily: Hydrophiloidea
This contains 7 families of beetles, of which the Helophoridae, Georissidae, Hydrochidae, and Spercheidae are aquatic, often living around water margins. The Hydrophilidae is also partly an aquatic family, but has a substantial number of species that specialise in using dung as a food source. The Sphaeritidae (‘False Clown Beetles’) and Histeridae (‘Clown Beetles’ – from the way they tumble about) are also feeders on similar decaying matter.

Superfamily: Staphylinoidea
Mostly comprising the largely predatory ‘Rove Beetles’ (Staphylinidae), which characteristically have shortened wing-cases, exposing abdominal segments, this Superfamily also includes four other families:
Hydraenidae (‘Minute Moss Beetles’ – aquatic species),
Ptiliidae (‘Feather-winged Beetles’ – minute beetles of decaying plant matter),
Leiodidae (known as ‘Round Fungus Beetles’, but also feeding on carrion or decaying plant or animal remains), and
Silphidae (‘Carrion Beetles’ – specialising in using dead animal remains as a food source).
The Rove Beetles also include the Pselaphinae (sometimes known as ‘Ant-loving Beetles’), the Scaphidiinae (‘Shining Fungus Beetles’) and the Scydmaeninae (‘Ant-like Stone Beetles’) that were formerly regarded as separate families.

Superfamily: Scarabaeoidea
This Superfamily includes the familiar Stag Beetle and its allies (Lucanidae), along with the ‘Dor Beetles’ and their relations (Geotrupidae, now including Odonteus armiger, formerly placed in family Bolboceratidae) that are well-known as dung feeders. It also includes the fairly large family of ‘Scarab Beetles’ (Scarabaeidae), many of which also feed on dung, and a related small family, the Trogidae.

Superfamily: Scirtoidea
This Superfamily consists of three families: the Eucinetidae (‘Plate-thigh Beetles’ – from the large coxal plate at the base of each femur, characteristic of the genus), of which only one occurs in Britain; the Clambidae (‘Fringe-winged Beetles’), very small beetles that live in decaying plant remains; and the Scirtidae (‘Marsh Beetles’) that occur in damp waterside vegetation and have aquatic larvae.

Superfamily: Dascilloidea
In Britain and Ireland, the entire superfamily (‘Soft-bodied Plant Beetles’) is only represented by a single species, Dascillus cervinus (Dascillidae) that occurs in calcareous grassland.

Superfamily: Buprestoidea
The ‘Jewel Beetles’ and their allies (Buprestidae) form the only family in Britain and Ireland, characterised often by their brilliant reflective colouration and long, narrow form, mostly developing in the timber of trees, some as leaf-miners.

Superfamily: Byrrhoidea
The principal family Byrrhidae consists of the ‘Pill Beetles’ and their allies, often characterised by their rounded shape and by being able to retract their legs into grooves on their undersides. Other families in the superfamily are largely at least partly aquatic, comprising the Elmidae (‘Riffle Beetles’), occurring in fast-flowing streams on submerged stones; the Dryopidae (‘Long-toed Water-beetles’), with characteristic, short antennae, living in water margin vegetation; Limnichidae, with one minute species found in aquatic habitats; the Heteroceridae (‘Variegated Mud-loving Beetles’), living in water margins; the Psephenidae (‘Water Penny Beetles’ – from the shape of their aquatic larvae), with one British species; and the Ptilodactylidae, with one recently introduced species occurring in glass-houses.

Superfamily: Elateroidea
This is a rather heterogeneous superfamily, comprising especially the family Elateridae (‘Click Beetles’), with their characteristic ability to suddenly flex their thorax against their abdomens, as a means of jumping to safety. The superfamily also includes the closely-related Eucnemidae (‘False Click Beetles’); the Throscidae, also similar to Click Beetles; the Drilidae (‘False Firefly Beetles’), with one British species; the Lycidae (‘Net-winged Beetles’), whose elytra show clear vestiges of the net-veining found in the forewings of other insect orders; the Lampyridae (‘Glow-worm Beetles’); and finally the Cantharidae (‘Soldier Beetles’ and allies), with soft bodies and often brightly coloured, thin elytra, conspicuous on flowers in summer.

Superfamily: Derodontoidea
The single species Laricobius erichsonii (Derodontidae) is a recent arrival from central Europe, occurring on coniferous and broad-leaved trees, where it feeds on woolly aphids. It has been used as a biocontrol agent in North America.

Superfamily: Bostrichoidea
A superfamily which, in Britain, contains a number of species regarded as pests of foodstuffs and timber. It includes the Dermestidae (‘Larder Beetles’) and the Ptinidae (name changed from Anobiidae in Duff (2012)) (‘Wood-worm Beetles’ and allies), as well as the Bostrichidae (‘Horned Powder-post Beetles’).

Superfamily: Lymexyloidea
This superfamily contains only one British family, the Lymexylidae (‘Ship-timber Beetles’) with only two, rather scarce representatives in Britain and Ireland: Lymexylon navale and Hylecoetus dermestoides, which develop in decaying trees.

Superfamily: Cleroidea
Clerid beetles fall into five families, of which the most conspicuous are the Malachiidae, often iridescent green and red in colour, and the related Dasytidae (together forming what was formerly regarded as the family Melyridae – ‘Soft-winged Flower-beetles’). The superfamily also includes the Phloiophilidae (1 species), Trogossitidae (5 species) and Cleridae (14 species, often called ‘Chequered Beetles’ – from their conspicuous striped or patterned colouration, sometimes mimicking bees or ants). Species are either predators or feed on pollen etc., and develop in the soil or in dead wood of trees and stems of plants, sometimes causing damage to crops.

Superfamily: Cucujoidea
A large superfamily, including some of our most conspicuous beetles, as well as some of the least conspicuous. It currently includes 19 families in Britain and Ireland, ranging from fungus feeders (e.g. Cryptophagidae – ‘Silken Fungus Beetles’), through pollen beetles and their allies (Kateretidae, Nitidulidae), food product pests (Silvanidae), ‘Root-eating Beetles’ (Monotomidae), to the conspicuous Coccinellidae (‘Ladybirds’). Only three of the families have so far been covered by this website: Phalacridae, Erotylidae and Corylophidae.

Superfamily: Tenebrionoidea
This is another quite large and diverse superfamily of 17 families, covering a wide range of species. The Tenebrionidae themselves comprise the ‘Darkling Beetles’ (worldwide a large group, often in desert areas) including the once-familiar Blaps (‘Cellar Beetles’), as well as flower-visiting species and some food pests, such as Tribolium species (‘flour beetles’) and the genus Tenebrio itself (‘Meal-worm Beetles’). The Mycetophagidae (‘Hairy Fungus Beetles’), Ciidae (‘Minute Tree-fungus Beetles’) and Tetratomidae (‘Polypore Beetles’) are fungus specialists. Other families include the Mordellidae (‘Tumbling Flower-beetles’) and their look-alikes the Scraptiidae (‘False Flower-beetles’), the Colydiidae (‘Cylindrical Bark-beetles’), the often scarce but also conspicuous Meloidae (‘Oil Beetles’), the very conspicuous Pyrochroidae (‘Cardinal Beetles’), and the ant-mimicking Anthicidae (‘Ant-like Flower-beetles’). Some are charismatic species of ancient timber, such as the Melandryidae (‘False Darkling Beetles’) and the Aderidae.

Superfamily: Chrysomeloidea
This superfamily includes a large part of the principal plant-eating species in the two main families: Chrysomelidae (‘Seed and Leaf Beetles’) and the Cerambycidae (‘Longhorn Beetles’ – from their long antennae). The two other families: Orsodacnidae and Megalopodidae are small families related to the Chrysomelidae. Many species tend to be conspicuous as adults, often with metallic colours, and quite a few are crop pests. A few are semi-aquatic. The ‘Longhorn Beetles’ include some of our largest beetle species, and mostly specialise in developing in timber trees.

Superfamily: Curculionoidea
Comprising 11 families in Britain and Ireland, these together comprise the weevils, mostly recognised by possession of long ‘snouts’ for feeding on plants. Some are bark beetles, while most live on their varied host plants. A very few are aquatic, and some are subterranean. Some genera also have conspicuous metallic or other colouration.

References
Duff, A.G. (2008). Checklist of beetles of the British Isles. 2008 edition. Wells: A.G. Duff.
Duff, A.G. (2012). Checklist of beetles of the British Isles. 2012 edition. Iver: Pemberley Books.
 

00 What’s new?

16th October 2016: New version of the Amara and Curtonotus (Carabidae) ID guide available to download. Includes the newly-discovered Amara majuscula.
25th March 2015: Lycidae (net-winged beetles) page updated with more info on Cosnard’s Net-winged Beetle Erotides cosnardi.
19th March 2015: Carabidae (ground beetles) page now with new and updated links to freely download all 15 of the ID guides produced by John Walters and myself.
19th March 2015: Scarabaeoidea page now with a link to freely download John Walters’ ID guide to Dor Beetles (Geotrupidae).
13th March 2015: New page on mounting cards for carding beetles.
6th March 2015: Spent some time updating, fixing broken links, tidying up and making the site look less neglected!
21st February 2015: New page on Scarabaeoidea (dung beetles, chafers, and allies) added. Includes important new resource for ID of Aphodius.
13th December 2013: Minor update to the Corylophidae page with a map of my Sericoderus brevicornis records.
7th December 2013: Minor update to Chrysomelidae page to mark the discovery of Longitarsus minusculus.
7th December 2013: Minor update to Staphylinidae: Steninae page.
7th December 2013: Drilidae (Drilus flavescens) page updated with extra photos thanks to Penny Green and friends.
7th December 2013: Minor update to the Corylophidae page to mark the discovery of Arthrolips obscura.
7th December 2013: Update to the weevil page, mostly dealing with problems that have been recognised in the True Weevils Part III RES Handbook.
7th December 2013: Minor update to the click beetle keys.
7th December 2013: Update to the pan-species listing rules to cover hybrids and species of hybrid origin.
10th May 2013: Update to the weevils page with a photo of the 2nd British specimen (?) of Bradybatus fallax.
12th April 2013: Steve Lane is the latest addition to the pan-species listing rankings in 15th place.
30th March 2013: Added a photo of Olibrus norvegicus to the Phalacridae page.
29th March 2013: Added an updated version (v5) of the Keys to British Byrrhidae and Limnichidae.
6th March 2013: Major update and revamp of the Carabidae pages, including a new version of the Carabid Crib.
6th March 2013: Total rewrite of the Missing carabids: Abax parallelus page thanks to info from Roger Booth!
5th March 2013: Another in the occasional series of pages on “missing carabids”, presumed extinct: Abax parallelus.
27th February 2013: Pan-species rankings updated for Seth and Sami Gibson. Link added to the Pan-species Listers facebook page.
26th February 2013: Oil Beetles and allies page updated following the re-discovery of Meloe mediterraneus and with a link to John Walters’ triungulin ID page.
26th February 2013: Added Richard Comont and Sally Luker to the pan-species rankings and updated the totals for Andy Musgrove and Graham French.
24th February 2013: Pan-species rankings updated for Stuart Dunlop, John Coldwell and Martin Harvey. See Martin’s page for a sobering graph showing the impact of parenthood on his tick rate!
24th February 2013: Staphylininae page updated with a couple of errata for the Lott and Anderson (2011) RES Handbook.
11th February 2013: All Staphylinidae pages revised and updated, e.g. to include links to download the out-of-print RES Handbooks by Tottenham and Pearce.
4th February 2013: Overview of the beetle families updated to follow the Duff (2012) checklist and to add many new links. The list of the useful sections of Joy (1932) whittled down still further.
3rd February 2013: Seed and Leaf Beetles (Chrysomelidae, Megalopodidae and Orsodacnidae) page added.
20th January 2013: With the very sad passing of Eric Philp on 8th January 2013, I have updated his pan-species listing biography.
20th January 2013: Pan-species rankings updated for Scotty, Graeme, me, Steve Gale, Tony Davis, Seth, Neil, Skev, Jon, Clive, Simon and Sami. Have I missed anyone?
20th January 2013: Not much activity on the website for a while as I’ve been busy with my new baby boy!
20th November 2012: Phalacridae page added with updated keys to this small beetle family.
11th November 2012: Jewel beetle (Buprestidae) page updated with links to a comprehensive online key to the British fauna by Mike Hackston.
13th October 2012: Pan-species lists updated for Seth Gibson, Scotty Dodd, Jonty Denton, Stephen Howarth, Clive Washington and Sean Foote.
11th October 2012: All the pan-species listing pages brought up to date and the rankings updated. Welcome to new pan-species listers Sean Foote and Tony Marshall.
12th September 2012: Added a new updated version of my identification guide to Amara and Curtonotus.
15th July 2012: Click beetle keys now updated with links to photos of all the species missing from Joy’s keys (only in the online version, not the PDF download).
28th June 2012: Drilus flavescens page now with pics of the rarely seen adult female.
15th May 2012: Added Eric Philp, Simon Davey and Danny Widerscope to the pan-species list rankings. Also a major upgrade to the pan-species pages to make future updates easier, thanks to Simon Mustoe of Wildiaries.
14th May 2012: Added a blogroll of blogs by pan-species listers and entomologists: knowledge, beauty, humour, inspiration … and lists! Scroll down a bit, on the left.
3rd May 2012: Web-spinner blog now updated: the specimen is now identified as Haploembia solieri.
29th April 2012: Page added on aleocharine staphylinids with a few basic ID tips … it’s a start!.
29th April 2012: Byrrhidae (Pill Beetles) keys updated with the addition of photos of the 4 Byrrhus species.
29th April 2012: Lycidae (Net-winged Beetles) page added.
29th April 2012: Drilidae (Drilus flavescens) page added.
29th April 2012: Meloidae (Oil Beetles and allies) page added.
29th April 2012: Tetratomidae page added.
29th April 2012: Erotylidae page added.
28th April 2012: Pyrochroidae (Cardinal Beetle) page added.
28th April 2012: Bark beetle (Scolytinae) and pinhole-borer (Platypodidae) page added.
28th April 2012: Weevil page added covering all Curculionoidea apart from the bark beetles (Scolytinae) and pinhole-borers (Platypodidae).
28th April 2012: Aderidae page added with new records of Vanonus brevicornis and tips for finding it.
25th April 2012: Scotty Dodd (7th), Richard Wesley (17th) and Stephen Howarth (25th) join the pan-species rankings. Updated totals for several other folk.
21st March 2012: Penny and Dave Green join the pan-species rankings, tied in 21st place. They’ve both written great articles on their lives as naturalists, recorders, conservationists, and pan-species listers: here’s Penny’s and here’s Dave’s.
7th March 2012: Broken link to the Patrobus guide now repaired.
4th March 2012: Six photographic ID guides to carabids now available to download directly plus three brand new carabid ID guides: Asaphidion, Poecilus and Patrobus.
4th March 2012: All the gen you’d need to rediscover Agonum chalconotum on the Clyde: anybody fancy a shot at glory?
11th February 2012: Tachyporinae (Staphylinidae) page: minor updates to keys, including mention of the 2 species of Mycetoporus recently added to the British list.
11th February 2012: Byrrhidae page updated with a new version of the key.
11th February 2012: Mordellidae page updated with a new version of the ID guide to neuwaldeggiana, humeralis and variegata, and a new table of ID sources.
11th February 2012: Dave Gibbs (2nd) and myself (3rd) updated in the pan-species list rankings.
3rd February 2012: Neil Fletcher (18th) joins the pan-species list rankings. Graeme, Steve and Skev updated.
27th January 2012: Corylophidae page added, including a key to the two British species of Sericoderus.
24th January 2012: John Coldwell (6th) and Stewart Sexton (21st) join the pan-species list rankings.
9th January 2012: Nicola Bacciu (9th), Matt Prince (10th) and Graham French (18th) join the pan-species list rankings.
7th January 2012: Byrrhidae (Pill Beetles): minor update of keys to version 2.
5th January 2012: Harpalus calceatus photo added.
2nd January 2012: Jon Cooter has posted some valuable advice on laurel bottles for storing and relaxing beetle specimens.
2nd January 2012: Jeff Blincow joins the pan-species list rankings.
31st December 2011: Added a review of British records of Harpalus calceatus (Carabidae).
31st December 2011: Tony Davis and Clive Washington join the pan-species list rankings.
31st December 2011: Byrrhidae (Pill Beetles) page added.
22nd December 2011: Sami Webster and James Harding-Morris join the pan-species list rankings.
15th December 2011: Cerambycidae (Longhorn Beetles) page added.
15th December 2011: Buprestidae (Jewel Beetles) page updated with help from Keith Alexander.
11th December 2011: Buprestidae (Jewel Beetles) page added.
10th December 2011: Sandwich Bay Coleopterists’ Meeting 2012: first announcement.
10th December 2011: Pan-species list update for Josh Jenkins-Shaw.
6th December 2011: Lampyridae (Glow-worms) page added.
29th November 2011: How to get your pan-species list and a breakdown by taxonomic groups out of MapMate: user guide added.
27th November 2011: Pan-species list updates for me, Graeme, Martin, Sarah, Steve and Seth: here.
17th November 2011: Mark Skevington joins the pan-species listing rankings. Updated lists for Jonty, Graeme, Jon, Steve and Seth: here.
7th November 2011: On the Cantharidae (Soldier Beetles) page there’s a new, updated Field Key to Soldier Beetles available for download thanks to Martin Harvey and Keith Alexander.
4th November 2011: Subterranean pitfall trapping for beetles page added.
10th October 2011: Cantharidae (Soldier Beetles) page added.
30th July 2011: Stuart Dunlop joins the pan-species listing rankings.
27th July 2011: Version 2 of the ID guide to Mordellistena humeralis and its two allies added to the Mordellidae page.
21st July 2011: ID guide to Mordellistena humeralis and its two allies added to the Mordellidae page.
19th July 2011: Carabid Crib updated to version 10 thanks to info from Clive Washington, Andrew Duff, Peter Hodge, Neil Fletcher and Dave Murray.
18th July 2011: Water-beetle (Haliplidae) test keys added.
12th June 2011: Pan-species listing pages updated, and John Palmer, Jonathan Newman, Seth Gibson and Robert Smith join the rankings.
12th June 2011: Ciidae (ciid beetles) page added.
12th June 2011: Staphylinidae pages updated following the publication of the new RES Handbook by Derek Lott and Roy Anderson.
29th May 2011: Click keys updated with an improved couplet on Adrastus/Agriotes thanks to Jim Jobe, plus a reference to AA Allen’s 1968 paper on Eucnemidae.
29th May 2011: Jonty’s pan-species list breaks 10,000. Updated the pan-species listing pages and rankings. Added the rules.
22nd Mar 2011: Major update to my pan-species list, now over 6,000.
9th Mar 2011: Clive Washington describes a new improved hooked pin.
7th Mar 2011: Mordellidae (Tumbling Flower-beetles) page added.
2nd Mar 2011: Good tip from Clive Washington for holding beetles under the microscope (see Comments).
13th Feb 2011: Carabid crib updated to version 8 with minor corrections.
13th Feb 2011: Sarah Patton joins the pan-species list rankings.
7th Feb 2011: Josh Jenkins-Shaw joins the pan-species list rankings.
22nd Jan 2011: Water-beetle (Gyrinidae, Noteridae and Paelobiidae) test keys added.
22nd Jan 2011: Dermestidae (hide, larder and carpet beetles) page added
22nd Jan 2011: Carabid crib updated to version 7 with additions on Patrobus, Oxypselaphus, Paranchus and Harpalus.
22nd Jan 2011: Listing pages thoroughly updated.
9th Jan 2011: A really good overview of the Suborders, Superfamilies and Families of British beetles added thanks to Trevor James.
9th Jan 2011: Test keys to the Ptiliidae (featherwing beetles) added.
9th Jan 2011: Techniques for studying beetles pages restructured and updated including some excellent advice from James McGill and tips on dissecting ptiliids and corylophids.
2nd Jan 2011: Derek Lott’s test keys to Philonthus added, completing the Staphylininae test keys
30th Nov 2010: Updated this posting: “Mystery Malthodes new to Britain?
26th Oct 2010: Carabid crib updated to version 6 (sorting out Lebia cyanocephala and my numbering error in v5 with Bembidion saxatile and B. decorum).
23rd Oct 2010: Derek Lott’s test keys to Gabrius added
11th Oct 2010: Derek Lott’s test keys to Bisnius and Phacophallus added
19th Sept 2010: a new entrant at 7th in the All-taxa List rankings!
19th Sept 2010: Carabid crib updated to version 5 (sorting out problems with Bembidion saxatile and B. decorum).
19th Sept 2010: Derek Lott’s test keys to Erichsonius and Neobisnius added. Test key to genera of Staphylininae updated to v3.
26th Aug 2010: a new entrant at 6th in the All-taxa List rankings!
22nd Aug 2010: Carabid Crib updated to v4.
22nd Aug 2010: Derek Lott’s test keys to Ontholestes, Platydracus, Tasgius and Cafius added. Test key to Ocypus and Tasgius updated to v3.
26th July 2010: Derek Lott’s test keys to Ocypus and Tasgius added.
26th July 2010: Updated the click beetle key, now on version 1.3.
21st July 2010:
Derek Lott’s test keys to Quedius and Heterothops added – sorry for the wait!
6th June 2010:
Tachyporinae, Habrocerinae, Trichophyinae and Phloeocharinae (Staphylinidae) page added, with keys.
30th May 2010: Added a ‘What’s New?’ column!
30th May 2010: The ‘immaculate’ carabid collection that John Walters and I have assembled.
29th May 2010: Derek Lott’s test key to Othius (Staphylininae).
29th May 2010: Do you need Joy?: my thoughts on Norman H. Joy’s legacy to British beetle studies, the current usefulness of his Practical Handbook, and the copyright situation.
29th May 2010: Updated the Click Beetle page to link to a new page on Joy’s abbreviations and conventions (to help people use Joy’s keys).

Driller killer: the solution … ?

Those who’ve been in contact fall into two camps: those who think the holes were probably caused by another mollusc, and those who think they were caused by a beetle. But tellingly, all the mollusc experts so far think that beetles of some sort must be responsible, and two have noted that they’ve seen holes like this in terrestrial snail shells in the Mediterranean.

As Richard Wright and others have kindly pointed out, there’s a 2004 book on “Natural enemies of terrestrial molluscs” with a detailed chapter on Coleoptera as predators of terrestrial gastropods by Bill Symondson of Cardiff University. Bill’s response must therefore be the most authoritative that I’ve received but is still a guess: “I would guess that these are the exit holes of drilid beetles, that parasitise many species of snails”.

The great thing about Bill’s response is that it has turned the mystery on its head – it’s not about what’s trying to get in but what’s trying to get out! In support of the parasite theory: (1) there are 5 separate holes – why would a predator need more than one?, (2) the holes are quite evenly spaced as they might be if 5 parasites had partitioned up the snail between them, and (3) one of the holes is right by the mouth aperture so there’s no way it was the easiest route of attack to get IN to the shell.

So, given that Drilus flavescens is the only drilid on the British list and it has been recorded not too far away to the south in Berkshire and Oxfordshire (map here), can we add it to the Buckinghamshire list? Maybe.

Andrew Duff dug up another interesting lead here. This person has lots of Garden Snail Cornu aspersum (formerly Helix aspersa) shells in their garden with one or two neat circular 4mm holes in them. Nobody on the wildaboutbritain forum seems to know what’s caused them but whatever it is must be the same beast that drilled the Grangelands Helix pomatia. However, the garden in question is in Lincolnshire! I could believe that Drilus flavescens exists at Grangelands – a superb calcareous grassland just north of the known range. But I find it harder to believe that Drilus exists in a garden in Lincolnshire!

For a definitive answer, Julia’s going to try and breed the parasites out in 2010.

Meanwhile, thanks to all those who’ve been in touch and if anyone has further suggestions, I’d be glad to hear them.