On Fri, 14 Nov 2014 14:25:59 -0800 (PST),
wrote:

Contrary to what most of these replies stated, tracking powered can indeed be harmful. At least one type (ZP tracking powder) contains phosphine which is released as phosphine gas when it hits water or acid (in a stomach or mouth). It is not intended to track where rodents go, but for them to track through it and then ingest it during grooming.

Hornswoggle.

Tracking powder is a simple as using ordinary flour from your pantry.
Locating the traffic pattern, where "they go". Be it a rodent, a
lizard, a snake (sidewinder), it does not need to be "harmful".

Fluorescent Powders and a UV back light will find the trail to the
hide out, sanctuary, rodent bunker...too.