A popular homemade ant-killer is soapy water. All you need is liquid dishwasher soap and boiling water. The mix ratio should be 1:4. Pour the hot soapy water down the ant’s nest hole. Repeat three times daily.
Apple cider vinegar is a cheap DIY ant-killer solution. All you do is pour vinegar in the ant’s nest hole and surrounding area. Repeat daily for five days.
Lemon eucalyptus tree oil is another natural ant repellent.
Nematodes are super tiny worms that devour ants. The micro-worms only eat ants and ignore other insects. They will not hurt ladybugs or dragonflies.