TERRO Outdoor Liquid Ant Killer Bait Stakes – Link

Amazon has this currently marked down to only $3.50.

• Kills the ants you see and the ones you don’t
• Targets ants outdoors before they can come indoors
• Ready to use; insert stakes, break tab, kill the colony
• See through bait monitor lets you know when it’s time to replace
• Reinforced ridges keep the stake firmly in the ground