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Ophonus: the arable weeds of the beetle world

This is a great time of year for finding species of Ophonus ground-beetles by checking the seed-heads of Wild Carrot Daucus carota. As the seeds ripen, the heads change from a flat-topped umbel into a more or less spherical shape with all the seeds on the inside. Ophonus like to sit inside the middle of carrot seed-heads, spending their days munching seeds. It’s quite easy to prise open the seed-heads and check for beetles.

Pair of Ophonus ardosiacus in a carrot head. Officially Nationally Scarce (Nb), this beetle has become quite common in recent years probably at least partly thanks to arable margin schemes.

Ophonus ardosiacus eating a ripening carrot seed

At least some species of Ophonus will also fly to light. O. ardosiacus is quite frequent in moth traps. One of the rarer species, O. melletii, has only been recorded seven times in the last decade but two of the records are from light traps.

It would be great to get more records of Ophonus, especially from moth-trappers. I would be happy to receive Ophonus specimens for identification from anyone and everyone. Details on posting live specimens here.

Of the 14 British species, only three could be described as at all common (rufibarbis, puncticeps and ardosiacus) and the rest are at least scarce and in some cases extremely rare. Many have clearly declined dramatically during the 20th century, in the same way that many once-common arable weeds such as Corncockle and Corn Buttercup have declined. Losses of the beetles are probably also related to agricultural intensification and the loss of areas of disturbed ground that have a diverse range of weeds, producing lots of seeds, year-in year-out.

I have a passion for these ground beetles. I have attempted to see all the British species, visiting last-known sites, often repeatedly over many years. But there are still five species I have never managed to find. At least four of those species I believe should still be findable in Britain if only I could work out exactly where, when and how. The other one (O. subsinuatus) has not been recorded since 1886 (Portland) and it would be an amazing discovery if it was ever found again in Britain. Four species of Ophonus are currently on the Biodiversity Action Plan list but several others are of equal concern.

I have just had a week’s holiday, and dedicated a few days to searching for Ophonus. It was great to see Ophonus melletii (two males) at long last, by visiting the best known area for the species at Cheam on Monday. As far as I know it was last seen here in 2004 by Martin Luff. I also found one O. schaubergerianus (previously recorded here by David Copestake in 1993), three O. ardosiacus and one O. puncticeps.

Ophonus melletii from Cheam

Ophonus schaubergerianus from Cheam

On Wednesday, I targeted one of the more recent (1988) localities for O. puncticollis near Hurley, Berkshire but the habitat seems completely unsuitable now. Later in the day I explored some field edges around Lodge Hill in the Chilterns near Princes Risborough and came up trumps with a new site for O. laticollis, a species which seems to be having a mini-resurgence on arable margins thanks to the ESA scheme and similar subsidies.

Ophonus laticollis at Lodge Hill (found dead). 3rd record for Bucks.

On Saturday, Jo and I day-tripped the Isle of Wight and worked the soft-rock Red Cliff, east from Yaverland out to the start of the chalk Culver Cliff. I was targeting O. cordatus again, a species last seen in Britain on Salisbury Plain in 1996. It was recorded from “Sandown, Culver Cliff” by W. Holland in 1903 and from “Red Cliff” by Howard Mendel in 1988. We found dozens of O. ardosiacus, several O. puncticeps, a few O. azureus and one O. rupicola (only the second I have found): O. cordatus must still be there but as so often in the quest to find rare beetles, doggedness is going to be the key to success.

Red Cliff, looking east towards the chalk of Culver Cliff. Ophonus azureus was found on the ground beneath the Wild Carrot plants in the foreground.

Ophonus rupicola in the grip

Amazingly, despite seeing seven species of Ophonus in a week, I didn’t see any of the commonest of them all: O. rufibarbis!

1 Comment

  1. John Murray says:

    Ophonous ardosiacus in nightly-operated actinic trap at Marshalls Heath TL 161 152 1996 July 12th and 2015 August 3rd.

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