Many people and small mammals consider black walnuts a delicious treat, but creatures of the insect world have a different take on the matter. The black walnut tree produces a strong-smelling, pungent substance called juglone, which is a natural insect repellent. You can take advantage of this strong scent and use the juglone-rich leaves and/or branches around your house as a natural repellent. But you'll need to be mindful of where you use the leaves and branches, because juglone can be harmful to nearby plants.
Pull a few handfuls of leaves from your black walnut tree.
Cut the leaves into ¼-to-½-inch pieces with scissors and put them in a measuring cup. Continue to collect and cut up leaves until you have approximately one quart, or four cups, of shredded leaves.
Sprinkle the leaf cuttings around the perimeter of your house relatively close to the foundation without touching the structure itself.
Allow the leaves to remain undisturbed for three weeks.
Collect the used leaves after three weeks and replace with new cuttings, following steps one through four. Repeat the process every three weeks for maximum effectiveness.