Formosan Tree Termites


Formosan termites have three castes within a colony: Reproductives (winged or wingless), soldiers, and workers (pseudergates). Formosan termites are identified by their soldiers or winged reproductives (Alates). Their nest are also easily identifiable. Formosan termite colonies may contain more than a million individuals.

Winged Reproductives: (Fig. 1)

Fig. 1 Formosan Subterranean Termite Alate
  • Body color is yellowish-brown in color and are
  • Bodies are12-15 mm (0.5-0.6 inch) in length
  • Have large ocelli (simple eye)
  • Their antennae contain more than 18 segments
  • Wings are >10 mm long and covered with dense golden hair
  • Wings have two heavily pigmented veins (costa and radius veins) near the front edge and no connecting cross veins.

Soldiers: (Fig. 2)

Fig. 2 Formosan Subterranean Termite Soldier
  • Tear dropped or egg-shaped head shorter than that of native subterranean termites.
  • Make up between 5-10 percent of a colony.
  • Very aggressive
  • They attack anything or anyone
  • Exude a small amount of a white, defensive secretion from a gland (fontanelle)

Workers (pseudergates):

  • White to off-white color
  • Difficult to distinguish from other termite species

Nests: (Fig. 3)

Fig. 3 Formosan Carton Nest

Formosan Termites often make aerial nests of chewed wood, saliva, and fecal material commonly called carton. They can be as large as several cubic feet and can be located above ground without soil contact.

Damage: (Fig. 4 & 5)

Formosan termites cause the same type of damage as the other subterranean termites. They cause more rapid damage than native subterranean termites. They have been known to attack more than 47 plant species, including citrus, wild sherry, cherry laurel, sweet gum, cedar, willow, wax myrtle, Chinese elm and white oak. Formosan termites feed on both the spring growth and the summer growth wood. They have also been known to eat through non-cellulose material, such as thin sheets of soft metal (lead or copper), asphalt, plaster, creosote, rubber, and plastic,searching for food and moisture.

Fig. 4 Formosan Subterranean termite railroad tie damage
Fig. 5 Formosan Subterranean termite tree damage


Distribution (Fig. 6 & 7)

Fig. 6 Formosan distribution in Texas

Formosan Termites, Coptotermes spp. come from China, Formosa, and Japan. They have been introduced to Hawaii and the Continental United States. It is thought that they were imported through the military supply crates being brought back following World War II. In Texas they were first identified in 1956 at a shipyard in Pasadena. Currently there are 19 counties in Texas that have been positively identified as having an infestation of Formosan Subterranean Termites. The majority of the sightings are along the Gulf coast with scattered sightings inland. The sightings inland are due to the transportation of infested soils or materials (ex. Lumber, wood crates, or mulch).

Formosan Subterranean Termites have been positively identified in the following counties in the state of Texas: Angelina, Aransas, Bexar, Brazoria, Collin, Dallas, Denton, Galveston, Henderson, Hidalgo, Harris, Jefferson, Liberty, Nueces, Orange, Rockwall, Smith, Tarrant, Travis. (Link to Texas Formosan Map)

Fig. 7 Formosan Subterraneaen Termite Distribution in the United States
Data provided by David Woodson, USGS

There is a federally funded research project being conducted on the Formosan termites through the USDA Southern Regional Research Center in New Orleans, LA, called Operation Full Stop

  What are Formosan subterranean termites and where did they come from?

Formosan termites are a non-native pest believed to have been brought into the United States after World War II on military ships carrying supplies from east Asia and the Pacific Islands. Their main points of entry were New Orleans and Lake Charles, La.; Galveston and Houston, Texas; and Charleston, S.C.

Where are they found? How many states are infested with them?

The termites have been found in Alabama, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Texas.

What's the difference between these termites and other termites?

Formosan termite colonies are much larger (containing about ten times the number) than native termite colonies. One important difference is that Formosan termites build more nests above ground. They attack live oak, ash trees and water-bound live bald cypress trees and are known to infest more than 50 living plant species. Because of their more aggressive nature and larger colony size, they are replacing the native species. When they do invade a home, they inflict more damage because of their greater numbers. They are also more difficult to control than native species for a variety of biological reasons. Since they can build nests above ground, they are able to avoid the traditional toxins that are placed into the soil for termite control. Also, there are so many members in a colony that they can find ways to penetrate breaches in treated soil. They can also begin colonies from above ground if sufficient moisture, food and a suitable environment exists.

How much damage do they cause homeowners?

Formosan termites cost consumers more than $1 billion a year, including the cost of repairs. In New Orleans alone, it's estimated that the pest infests as many as 30 percent of the historic live oak trees and can cost individual homeowners several thousand dollars a year in damage and control costs.

How do I know if I have Formosan termites?

The best way to detect this pest is to consult with professional pest control operators and have annual inspections. A homeowner can help by maintaining a constant vigil for signs of the termites, including looking for mud tubes on slabs, foundations or piers. These tubes are a sure sign of termite presence, but may represent an old infestation. Tiny holes appearing in walls or ceilings should be examined by a trained professional to determine whether they are caused by termites or other wood-destroying insects. While a few alates (flying termites) may come into a home during swarming season, the appearance of more than a few termites flying inside the home or deposition of many wings may indicate an active colony hidden within the walls of a home. Not all termites are Formosan and it takes a practiced eye to know which termite is present. Some drywood termite alates look very much like Formosan alates at first glance. The methods of control of these species are very different, so accurate identification is essential.

Can I apply my own treatment?

There are some termiticides available from do-it-yourself centers, but proper application and strict adherence to label directions are absolutely essential to effective control. Termite galleries (tunnels through which termites travel) may be 1/32 of an inch in diameter, so even a tiny area of untreated soil could allow termites to avoid a "treated" area. Some states have recently allowed do-it-yourself baiting systems to be sold, but again proper application and strict adherence to the label instructions are imperative for them to be successful in termite control.

Professional pest control operators (PCO) have the experience and insight needed to help design the most effective treatment program. You should familiarize yourself with as much information about termites as possible and talk to several companies to determine all of your options. Be certain to understand what the operators propose and get bids in writing so that you can compare the various proposals. There are several valid options for termite control and you have some time to make comparisons, but termite infestations will not "just go away." These termites can dig underground tunnels in untreated soil bypassing treated soil to invade your home. It takes a trained professional to detect all possible entryways to your home.

Among the many options you will be presented are fumigation, which kills termites in the walls of your home, but not ones hiding in the soil below. Usually, the PCO recommends a soil treatment in combination with fumigation to prevent the underground termites from invading your home again. New monitoring and baiting technologies have been developed and are successful in controlling both native and Formosan subterranean termites.

Can't I just have my house chemically treated for termites?

Although you should talk to a professional pest control operator about treatment, you can still reduce some of the risks of infestation by reducing or eliminating water sources such as leaky pipes and roofs; removing any wood and debris in contact with the soil, like wood trellises connected to homes; replacing damaged sills and floors, and sealing cracks in concrete and other structural materials. Formosan termites can eat door frames, window sills, rafters and wall studs.

Many different types of termite treatment exist. Most are designed to prevent termites from invading your home by repelling them from the immediate area of treatment. These products are designed to last for a relatively long period--more than five years--but each will break down eventually. The products must last at least five years in order to be registered as a termiticide. Different soils and soil conditions affect the rate of breakdown. Activities that disturb the soil or addition of new soil over the treated areas allows termites to tunnel through untreated soil.

A preconstruction treatment regimen and regular inspection are needed to keep termites at bay. New monitoring/baiting techniques are designed to work either alone or in conjunction with soil treatments. These systems use wood blocks that are inspected at regular intervals to determine termite presence and activity. Only when there is activity are the blocks replaced with a toxin-treated food source which the termites eat and share with their nestmates, resulting in severe population reduction of the colony or even death of the colony. These methods use much less toxin than soil treatments and represent an aggressive approach to termite control rather than the protective approach used in the past.

My house is made of brick. Is it protected against Formosan termites?

Not necessarily. These termites can eat door frames, window sills, rafters and roofing in addition to the wooden framing behind the brick of your home. Some new homes have steel framing to prevent structural damage from the termites, but the termites can eat many items containing cellulose, including picture frames, furniture and paper. No home is "termite- proof" unless there is no cellulose within for them to consume. Some new buildings and homes have suffered from Formosan termite damage.

How long does it take Formosan termites to cause severe damage?

It generally takes a few Formosan termites up to 10 years to establish a large colony. However, if the nest is already large, the termites can cause devastating damage to homes within a short time. The biggest problem in this regard is that you often don't know that they are present until they have already done substantial damage. These are insects which live in moist dark places and are not apt to show themselves to you. Protection against infestation is probably the best approach.

Is there a particular place I should look in my house to find these termites?

Any place where wood is in contact with the soil, like wood trellises connected to the house; where there's a water source (such as leaky pipes), like in the basement or behind walls; or where there's structural damage, like cracks in the concrete or in the floors. Check the outside of your home for termite trails--mud tubes 1/4- to 1-inch wide. Look carefully at nearby trees for mud trails which are sometimes more evident after a rain; check for mud deposited well above ground in tree branch notches or in branch stubs. These signs could be evidence of termites lurking in the trees that could also infest your house.

What are flying termites or termite swarms?

These flying members, called alates, are mature termites that fly off to mate and establish new colonies. The flying Formosan termites are tan colored, generally swarm at night and shed their wings after a swarm.

Is there a certain time of year I should look for termites?

Mature Formosan subterranean termites typically swarm in the evening on warm, humid, windless evenings from the end of April through June. During the rest of the year, infestations can be detected by looking for the signs of Formosan termites, including mud tubes and tiny holes appearing in indoor ceilings and walls.

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