Terro Mosquito Repellent is an easy to use granular product made from a blend of natural botanical oils, including citronella. The repellent’s effectiveness lasts up to three weeks. The 100% natural granules are safe to use around people and pets. Simply sprinkle the pleasant smelling repellent around the desired area. How it works the repellent releases a scented botanical vapor that disorients the mosquitoes, keeping them from detecting the scent of people or pets in the immediate area. Pretty tricky.