Non-infested termite mounds have no real use but for decoration. However, infested termite mounds are a different story. Once broken in any way, termites will appear and rush towards the player. When they get close enough, they'll explode, often breaking more infested termite mounds around them and unleashing more termites.
Unfortunately, both types of mounds look exactly the same, so you never know whether you will be attacked by those nasty buggers or not.