Termites are one of the most abundant insects in the world. They can be found in rainforests up to the deserts. They're also the most destructive. The most effective and surefire way to eliminate a termite colony organically is to find the queen and put her to permanent sleep. One kind of fungus is said to infect termites - metarhizium anisopliae. It's locally available but used only for the control of weevils and other beetles.