I wasn't sure whether to post this here or in the organic gardening forum, as mud dauber wasps would be a great natural caterpillar and spider control (with one species that also seems to specialize in Black and Brown widow spiders)
They are also amazingly docile compared to paper wasps, almost never stinging exept under extreme duress (IE being roughly grabbed or if a baby popped one in it's mouth).

The only downside I see is that, lacking a better alternative site, they may make thier nests on the side of buildings, which some people find unattractive.

Therefore, I was wondering if there might be a house that could be built specifically for their use, but the only mention I have found is of them and Paper Wasps taking over bathouses, and how to prevent them by making the seperate compartments 3/4 inch wide and having the dividers run all the way to the top. (Apparently, the paperwasps at least find 3/4 inch compartents too narrow to comfortably make a nest in).

This got me wondering:
Could a simplified and scaled down version of a bat house be made with compartments narrow enough to discourage paper wasps, but wide enough to admit mud daubers (who seem to have a narrower nest)?

This leads to my main question for bat house users:
Are there any bathouses whose compartment widths seem to permit mud daubers, but also discourages or prevents paper wasps from moving in, and if so, how wide are those compartments?

Here is a link that might be useful: Batcon bat house plans