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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.


9 Comments

  1. paul leiyton says:

    Found large female on work lunch break. I removed from public path and onto verge. Female was also accompanied by male (presumably). Male looked like soldier beatle but a third of the size and was seamingly running over and around female as if nursing/protecting female on its awkward journey. I found this pair at Poundbury west ind est. In Dorchester, Dorset DT1 2PG on 25/06/2013. Unfortunately no photos taken.

  2. markgtelfer says:

    Nice one Paul, very envious!

  3. Penny Green says:

    We had two mating pairs of Drilus flavescens reported in Sussex at the beginning of July 2013, one in East Dean (nr Eastbourne) and one in Lewes. Both were photographed if you would like to see them!

  4. markgtelfer says:

    Thanks Penny. It would be good to add those photos to this page if possible.

  5. Paul Leiyton says:

    18/06/2014 This week two more sightings in the same location as last year. Poundbury west in Dorchester. DT1 2PG. First was a solitary female. A few days later a mating pair. This time i managed to take photos and short videos on each occasion. How to upload?

  6. Chris Matcham says:

    I think I found a Drilus larvae eating a snail in my front porch (Hampshire) yesterday (01/09/14). I’m a mammalogist and know little about beetles but I can send you pictures for I/D confirmation if you would like them.

  7. Brian cartwright says:

    I took a photo of a larva, was told it was a Reed Dagger but had conflicting opinions. Today received an email from Mr Florin FENERU of Natural History Museum giving identification and directing me to your site.

  8. Chris Matcham says:

    Dear Mark,
    I found a D. flavescens larva last year consuming a snail. Just found another one crossing a footpath nearby so I saved it by putting it in the vegetation at the side. Grid ref of sighting was: SU 58663225
    29/06/15

    Chris.

  9. Chris Matcham says:

    Found two D. flavescens larvae in my garden this morning. One in a snail and one curled up in a hedgehog feeding box. That’s 4 this year. Common as muck round these parts! SU 587322

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