What's This?

[kansas]

I just noticed the attached on the outside wall of our house by the front door.

I guess it's the nest of a very small wasp but I haven't caught sight of the owner yet.

Any ideas?

[mike strand2]

Possibly a wasps nest entrance.

[Devil]

Ootheca? https://en.wikipedia.org/wiki/Ootheca

[PW in Polemi]

It is not just the entrance, it is the whole nest, made of mud, for a single egg from, I think, a small wasp-like insect.

[kansas]

Having looked at it closely, and google'd, we think it's a mud dauber's nest and the emerging offspring will probably enlarge the hole.