Dung beetle and larva ID please

[gbvnh1]

Hi All!

I hope your Autumnal foraging is going well!

Last weekend I was back in the New Forest and found what I presume to be a type of Dor Beetle in pony dung. Trouble is, this was about half the size of the regular dor beetles, Geotrupes stercorarius, that I come across in summer. It was max 10mm, as you can see from the scale against my fingers.



At the same time I was coming across dung beetle larvae in older pony dung. I thought that dor beetle larvae are found underground, and so larvae like this above ground must be from some aphodius species. But they're so much larger than the aphodius beetles I find here in the summer that I'm at a loss to know what they're going to turn in to.



Can anyone shed some light for me?

Thanks!

[Klaas Reißmann]

Hi,

the beetle surely is Geotrupes (Anoplotrupes) stercorosus. Typically found in forrests in horse- or ponydung, but also found in other dor and even in old rotten funghus and carion.

As you told right, the larvae is not of a Geotrupes. I don't know the size of these larvae so I can't tell if it is typical size for Aphodius or not. But Aphodius are the ones that normally can be found in dor. Onthophagus, as far as I know, go underground, too. Best would be, if you can do so, to breed them. If it is successful we maybe can even tell the species.

Regards
Klaas

[gbvnh1]

Thanks Klass.

If this is the generic type of dor beetle, how do you account for the considerable difference in size between the individuals of the same species that I've been finding? This example appears smaller than the minimum size quoted in my reference guides.

The larvae were about 20mm when outstretched, if that helps? Even accounting for the larva being twice the size of the beetle it turns into, the larva seem too big to be aphodius ...?

I might consider taking one home to see what it turns into if (a) its generally considered acceptable for a non-rare species and (b) the missus doesn't object too strongly!

Cheers

Pete

[gbvnh1]

Sorry Klaas - spelt your name wrong - apologies!

[Paul mabbott]

As usual, I would be very cautious at putting a name to these photographs: the features to differentiate between the three common species of Geotrupes are not visible. However on size alone I would go with Geotrupes stercorosus which is said to be 12-19 mms long. Any geotrupid <16mms is usually G. stercorosus.
Geotrupids, like most beetles show a degree of sexual dimorphism in size - males being generally a couple of millimetres shorter than females.

It's not unusual to find the three common UK species on the same site.

[gbvnh1]

Thanks Paul

[Klaas Reißmann]

Hi everybody,

@ Pete

The wrong spelling of my name is strange to me, but I'm more or less becoming accustomed to it. I know it from my very short time in the states and I even know it from my three summerholidays I spend in South Devon on a farm. It was always said Klass instead of Klaas. So don't worry about it to much.

The beetle:

You aksed for Geotrupes stercorarius, but the one you took your photo of is another species Geotrupes (Anoplotrupes) stercorosus. this is two different species and not a mistake in the spelling.

The larvae can be ok by this sizw for Aphodius, so far if there is aphodius rufipes in GB. But as I told you: try to breed them. I don't think it is a rare one..., not in horse dor.

@ Paul

You are right in beeing careful with those species of Geotrupes stercorarius, Geotrupes spiniger and Geotrupes mutator. I wouldn't try to identificate those three species on a photograph. But Geotrupes (Anoplotrupes) stercorosus is absolutely no problem to identify, even on a photograph, depending on the perspective the photo was taken of. Here it is no problem. This is absolutely surely G. (Anoplotrupes) stercorosus, nothing else, even without knowing the size.

Regards
Klaas