bête noire. persona non grata

In 2004, I asked Merriam-Webster the following question. Neil S. Serven from the editorial department replied as follows.

Q: Bête noire means “a person or thing strongly detested or avoided: bugbear.”

Persona non grata means “personally unacceptable or unwelcome.”

Does persona non grata refer exclusively to people, or, like bête noire, can it also refer to things? If the latter, how do bête noire and persona non grata differ?

A: A survey of usage shows that persona non grata is used almost strictly in terms of people and not things, such as in the following example, which comes from USA Today (9/1/2004):

[Senator Zell] Miller is persona non grata in his own party for becoming the first keynote speaker from the opposition party at a national political convention.

There are occasional examples of this term in reference to nonliving things, such as the example below, but overall these are very rare:

The [stadium] project was persona non grata to city officials who rebuffed attempts to take a second crack at a tax increase to pay for the stadium.

Although the two phrases are quite similar, they are not exactly synonymous. While bête noire refers to things that are generally detested, persona non grata usually refers to things that are unwelcome among the members of a particular group.

Also, while bête noire is used in English as a noun, persona non grata usually appears as an adjectival phrase. Therefore, it would be incorrect to use persona non grata with an article such as “a” or “the,” as in, “He is a persona non grata.”