Not just urban: The Formosan subterranean termite, Coptotermes formosanus, is invading forests in the Southeastern USA

Coptotermes formosanus, known in its native China as the ‘House White Ant’, was introduced to the southeast USA likely in the 1950s, where it is known as the Formosan subterranean termite. In the USA it is best known as a pest of buildings in urban areas, however C. formosanus also attacks live trees along streets and in urban parks, suggesting it may be able to invade forests in the USA. A survey of 113 forest patches around Charleston South Carolina and New Orleans Louisiana, where C. formosanus was first recorded, found that 37% and 52%, respectively, were infested. Resistograph measurement of internal hollows in tree trunks in forest patches infested with C. formosanus found infested sites contained more and larger hollows compared with non-infested sites. Compared with forest patches free of C. formosanus, infested patches had 32% more trees with hollows in Charleston, and 115% more in New Orleans. Similarly, compared with patches free of C. formosanus, hollows were 2–3 times larger in infested patches in Charleston, and 2–6 times larger in New Orleans. Quercus (oak) and Acer (maple) were the most damaged trees in Charleston, whereas Carya (bitternut hickory), Taxodium (bald cypress), Nyssa (blackgum) and Liquidamber (sweetgum) were the most damaged in New Orleans. As termite damaged trees are more likely to die, these differing damage levels between tree species suggests that C. formosanus may alter community structure in US forests.