Sebum

Sebum is secreted by mammals.  It is also the material that rodents leave behind as they run across surfaces.  This material collects on hard surfaces and is visible on light colored surfaces like wires, concrete and wood. In this photo the light colored area is the stone wall and the dark wood beam is visible at the top.  The beam stops the progress of the rodents along the sill so they run down and under, leaving the sebum visible on the stones.  Securing or placing a trap right over the sebum marked runway will lead to success.  To make the trap more attractive, rub the sebum onto the trap trigger. -Lauren Greenhow, General Manager, GreenHow, Inc. GreenHow.com. Effective Organic and Low Impact Solutions, Lawn Care, Pest Control and Termite Control in Newton and Metro Boston.

Sebum rub marks visible top right of photo