Around '62, whenI had the subsidiary job of Fire Officer at Linton, my firemen told me that a "pre-mix" of foam agent and water, sprayed on these pests without air-injection into foam, would render them unapproachable by even their nearest and dearest for quite some time (and many baths) - for they stank to high heaven.
Don't know if it was true, and if so where it was tried.
D.