What @Countryboyjvd1971 was trying to telling you is to use food grade DE if you don’t want to spray anything on your buds, DE is for Diatomaceous Earth Food Grade like this
You sprinkle a bit on your plant with it. Insect Pest don’t like walk, crawl or make any travel on DE, it’s like they walk on breaking glasses.
Spinosad can be use safely until 1-2 weeks before harvest.
And washing your harvest. It’s best if you give a bath of water with a bit of hydrogen peroxide in it, like this
It’s for washing any residue of all kind, not only powder mildew, and prevent any dropping that you’ll may miss to cause bud rot during the curing processus and to avoid bad pathogens that dropping may have held.
It’s for your safety.
For the dropping identification, well, no body can do it with “certitude”, even the best entomologist can’t, without lab analysis.
You even don’t specify in what region in the USA you are living in… It would help a bit, but not that much anyway, lol
I have studied in Bioecology and Applied Ecology, so I know what I’m talking about.
So, I only can guess that’s maybe a cockroach or\and a thumbtack droppings, but without lab analysis, it’s a “Hail Mary” guess.
It could be something totally unexpected like a vole or a field mouse, check for “munchies”, eat away scars…, who knows…
In hope that’s helping you a bit, don’t hesitate to ask further questions, @BayPros