On Fri, 16 Dec 2016 20:06:45 -0600, Vic Smith wrote:

You'll have to experiment now. The old days, when you knew what
worked and could get it, are gone.

Since posting previously, I have been thinking about the non-toxic
insecticide diatomaceous earth, which is mostly silica.

Toothepaste also seems to be a likely candidate. I'll followup after
experimenting.