Keep ants from entering your house with TERRO outdoor ant killer. Our leading outdoor ant killer provides instant knockdown and long-term control against ants and other unwanted home invaders. An easy-to-use, precision spray tube allows you to deliver barrier spray in hard-to-reach places up to 10 to 15 ft away. When sprayed, the outdoor ant killer expands upon hitting the surface and leaves an invisible residual deposit. TERRO outdoor ant killer is ideal as a perimeter barrier around foundations, doors and windows. It is especially useful outside in early spring when ants emerge and attempt to enter the house. Use again in the fall when ants attempt to come inside for the winter.