Identification

• The subterranean termite species causes damage to a variety of trees with citrus trees ranking among those affected. White or yellow in color and measuring about 1/5 inch, the subterranean termite looks similar to an ant, according to the University of Florida Institute of Food and Agricultural Sciences article, "A Guide to Soil Insect Pests Identification." Another variety called the Formosan subterranean termite--a native of China and introduced to the United States via World War II military ships--also causes damage to citrus trees. The Formosan termite, brown or yellow in color, measures about 1/2 inch in length, writes Xing Ping Hu, Auburn University assistant professor and extension entomologist, in the article "Formosan Subterranean Termites."
  
  

Habits

• Subterranean termites live in the soil and develop colonies comprised of "reproductives, workers and soldiers," according to the AgriLife Extension Texas A&M System article, "Subterranean Termites." The workers perform the duties of the colony, creating the nests and feeding the other termites. Wood and other cellulose-containing sources serve as termite food, even though termites cannot digest cellulose. Microorganisms living inside the termites turn the cellulose into a digestible substance.
  
  

Tree Symptoms

• Damage to citrus trees appears as bark removal "from the tree crown between the soil line and scaffold roots," according to the article, "A Guide to Soil Insect Pests Identification." The termites sometimes move up along the trunk, damaging the tree, beneath wraps used for cold season protection or put in place to prevent sprouts. Formosan subterranean termites, however, can hollow a tree trunk, filling the hollow with a nest, Hu writes.
  
  

Tree Damage Factors

• Subterranean termites tend to show up in orchards or trees planted in areas formerly inhabited by palmetto or pine trees. Remnants of wood in the soil from these cleared trees serve as food for the termites. When this supply ends, the termites then turn to the new trees planted there, according to University of Florida Institute of Food and Agricultural Sciences article, "Protection of Young Citrus Trees from Damage by Subterranean Termites."
  
  

Prevention/Solution

• One cause for the attack on citrus trees results from planting in an area where a known termite food source, pine and palmetto trees, became scarce. Though using insecticides can kill termites on trees, treatment remains temporary. Removing the soil at the crown of the tree, too, can offset damage. A more effective treatment system involves using several measures together such as insecticides, soil removal and shallow planting of citrus trees.