If termites are attacking a live tree in your yard, the culprits are likely formosan termites. This variety of termite is the only one that feeds on live trees. However, if your live tree has dead limbs or disease has compromised the pith or cambrium layers, the culprits may also be drywood or subterranean termites. Nature's recyclers, these species of termite only eat the dead wood of the tree. But no matter the species of termite, it is important to act fast or the termites attacking your live trees may move on to your house.
Remove any dead wood from the tree. If the termites attacking your tree are subterranean termites, they will move on once their food supply is removed.
Treat the tree yourself. Purchase a liquid termiticide like Termidor from your local home and garden center and spray the tree. The termiticide should be sprayed all over the bark. But before you spray, investigate any areas where you see termite activity or damage. If any bark can be pulled back to reveal termite tunnels or damage, do this before spraying the bark of the tree. Then pour the pesticide around the base of the tree. When it soaks into the soil, it will create a barrier around the tree's base.
Protect your home. Once the termites have been evicted from your tree, survivors may look for food in your home. Protect it by placing bait traps around its perimeter. Once termites eat the bait, they will take it back to the colony and kill it.
Call a tree doctor to make sure that your tree is healthy. Termites typically prey on unhealthy trees or trees that have dead wood as a result of disease.
Call an exterminator. While spray termiticides work in many cases, a professional exterminator will better be able to access termite damage by drilling holes in the tree and injecting it with a foaming termiticide. He or she will also be able to inspect your home to make sure that you do not have a termite problem there.