Solitary burrowing bee

[Herd900rd]

Was this hole made by a solitary burrowing bee? Does such an insect exist even? There are usually several summer onwards on the Quantocks, almost like holes made by walking poles but larger, always nearly perfectly circular, and they have their associated spoil heap of soil right by.

[Geoff F]

Unless you have very thin fingers that hole looks a bit large for the many varieties of bees and wasps which create underground nesting sites.

Here is an example that I photographed earlier this year.



This Mason Wasp (Odynerus spinipes) builds a protective chimney around the burrow while some other bees and wasps block up the hole. However, burrows under construction may still be straight holes and some species seem to leave the burrows uncapped.

But in all the cases that I have witnessed the burrow spoil is well scattered around the area and not just piled up anywhere.

One option that I have seen previously is birds digging for the bee/wasp larvae. Alternatively, especially as it is getting a bit late now, how about a small rodent, or similar mammal.

But let's see what answer the more experienced naturalists suggest for this question.

[eucera]

How about Minotaur beetle holes? The ones you show look way too big for any mining bees

[Herd900rd]

I thought the clean shape and regularness of the circular hole would help identify it. I wouldn't expect something chasing or looking for prey to be as precise and tidy. My finger I would estimate to be just over a centimetre across. They aren't by any stretch of the imagination thick manly objects. The spoil starts by being like a volcano, with the caldera as the hole central, but usually gets spread around over time, and I think the resident sometimes sites the hole near droppings. I measured the hole depth with a blade of grass once. From memory it was about 5 cm deep. Straight vertical, not at an angle into a bank.

[Herd900rd]

Thanks, I'll investigate Minotaur Beetle.

[Geoff F]

Yes, holes around or beneath dung could well be Minotaur beetles.