Boric acid is fatal to insects. It is often used in the form of a dust or powder for baits. Ants, for example, think the formulation is food and take it back to the nest. The poison is passed around and those that eat it die.
Natural ant control can have several meanings. Some people intend it as non-chemical methods. Others mean a program with natural insecticides. Still others define it as using natural products extracted from the earth.
There are several types of effective ant control chemicals. Liquid insecticides either repel ants or poison them. Dust insecticides are used inside walls and poison ants. All types of baits are used to poison, as well.
Not all ant control methods are appropriate indoors. Many treatments can be harmful to humans and pets. Non-toxic baits are good for use indoors. Locating the nest helps with treatment, including targeted preventative action.