I've put a 10 baht coin in the corner of the photo to show relative size.

It seems to be some kind of fly or bee, and creates a hard tubular shell, sometimes of quite remarkable length. Seems quite delicate, but for the size and shape, quite strong. Slightly curved, probably as result of gravity. There are two pieces of the tube in the photo, one on the left which has broken off, and the other coming straight up from the stone or concrete, which seems to be the common site of these tubes.

[Edit} added second photo

Edited October 9, 201015 yr by JusMe

Looks like a Mud Dauber tube:

Organ Pipe Mud Dauber

More mud dauber

Thanks, Tywais, but I don't think that's it. The tubes are single rather than in any kind of "pipe organ" grouping, they're about half an inch in diameter, and only attached at the bottom, growing up into the air. They're hollow right the way down, rather than with cells that would hold eggs and food. Also, the web sites seem to indicate that the mud dauber wasp is solitary, and there is quite a group around these tubes.

Maybe I'll try to examine and even get a photo of one of the insects themselves in the morning.

Could this be some sort of fungus growth and not an insect?

Wasp, squash it.

Break one of the tubes open and see if it's full of dead spiders.

If you caught one of the insects coming in and out, then you could identify it.

I am sure it is a type of wasp though.

I think it's probably some kind of wasp, but still not sure. The tube is hollow right the way down with no spiders. And definitely insects, not fungus, as shown by the collection at the opening.

Catching one of the insects won't really help me much - I've looked about as closely as I can, but ignorance can't be improved without some knowledgeable input - which is why I turned to TV.

Took this shot a few minutes ago - see the collection of flies or wasps at the opening of the tube.

Its a type of fly , rummer has it they have no teeth, they don't bite but can give a nasty suck.