Formosan subterranean termite (Coptotermes formosanus)

(Photo credit to termiteweb.com)

Coptotermes formosanus is the most damaging termite found in Hawaii. It was first discovered in Oahu and subsequently spread to other neighboring islands in Hawaii.  The peak period for swarming is in May and June. Primary reproductives, or “alates” or “swarmers”, have four wings of about equal size and shape, eyes, beadlike antennae (not bent), and no constricted “waist” (as in ants). Subterranean termite alates are covered in tiny hairs, including the wings. The wings have no “cross-veins”, only two thickened veins running the entire length of the wing. The body of Coptotermes formosanus alates are 6 to 7 mm long and brown in color. It will be up to 12 to 15 mm long with wings on it. Near the distal (away from the body) tip of the wing, a faint yellow band is sometimes present (costal band). The workers are about 5 mm long and pale yellow with the mandibles lacking teeth. For the soldier, the size is about 6 mm long and has an oval-shaped, light brown head and dark brown mandibles. Soldiers have orange, tear-drop shaped heads with curved black mandibles. The soldiers’ bodies are whitish and soft (similar to workers). Soldiers can secrete a glue-like substance (defensive secretion) through a pore on their head when disturbed. Subterranean termites also have higher numbers (~10% of the colony) of soldiers than drywood termites (~1% of the colony). The colony of this species is always underground or under the soil, and moisture is crucial for the colony's survival. Due to their underground nesting habit, the infestation is sometimes difficult to be noticed until severe damage has been done by the species.

Asian subterranean termite (Coptotermes gestroi)

(Photo credit to termiteweb.com)

Coptotermes gestroi is endemic to Southeast Asia but has been spread to other parts of the world over the last century. This species has caused tremendous damage and threat to wood structures. In Hawaii, the presence of Coptotermes gestroi was first discovered in 1963 in Oahu and there was no second infestation until the late 1990s. The second infestation was found in the building located on the West side of Pearl Harbour. Currently, there are no Coptotermes gestroi recorded in other islands other than Oahu. Alates are dark brown and smaller (total length with wings less than 12 mm), with wings less than 10 mm long. Coptotermes gestroi wings do not have a costal band. Coptotermes gestroi alate heads also have visible crescent-shaped “antennal spots” near the ocelli (simple eyes, oval), that are not present on Coptotermes formosanus. The physical appearance of Coptotermes gestroi is similar to Coptotermes formosanus. The identification of both species required technical expertise and sometimes needs microscopic examination.

West Indian drywood termite (Cryptotermes brevis)

(Photo credit to padil.gov.au)

Cryptotermes brevis is grouped under Family Kalotermitidae, or generally known as drywood termite. This species is well known as one of the most damaging drywood termites in Hawaii. Alates are about 10 to 11 mm long with the wings. Soldiers are about 5 mm long and the head is brown to reddish-brown in color. The head of the soldiers are constricted and highly wrinkled. This species normally infests dry wood and does not have a connection with soil. Furniture, woodwork, and seasoned wood could be the target infestation for this species. Drywood termites will remove fecal pellets (or known as frass) from their feeding galleries.

Indo-Malaysian drywood termite (Cryptotermes cynocephalus)

Cryptotermes cynocephalus is another species of drywood termite found in Hawaii. However, its distribution is more restricted compared to Cryptotermes brevis which has a wider distribution in Hawaii. Similar to Cryptotermes brevis, this species also infest dry wood products.

Lowland tree termite (Incisitermes immigrans)

Incisitermes immigrans is grouped under drywood termite. This species rarely infest buildings. They normally live in living or dead dry wood and found predominantly along coast.

Forest tree termite (Neotermes connexus)

The body length of Neotermes connexus alates are 17 to 18 mm long with the wings and is pale brown. This species normally found in forest areas while living in the dead wood, wet wood, or living trees. In Hawaii, this species generally found above 500 ft elevation and seldom infest buildings.

How to differentiate winged form of ant and termite?

(Photo credit to termitemd.com)

The winged form of ant has a narrowed or constricted waist and elbowed antenna. The front wing is larger than the hind wing.

The winged form of termite has a thick waist and straight, beaded antennae. Front wing and hind wing are equal in size.

Damage of Subterranean Termite

Subterranean termites may cause serious damage to structures (e.g., homes, buildings, fences, etc.), furniture, trees, wiring, paper products, plastics, soft metals, and agricultural products. Subterranean termites can gain access to your home through the soil, cracks in concrete/foundation, and tubes they create from the soil to the wood (“mud tubes” = branched tunnels about ¼” to ½” in width). When access to wet wood (e.g., areas of pooling, leaks, sprinklers, air conditioner condensation, etc.) occurs with no connection to the ground, an “aerial” colony may form. Damage to wood may be difficult to detect. Signs may include soft, sagging wood, moist, or hollow wood, and peeling, blistered, or cracked paint. Subterranean termite-damaged wood is typically “lined”, or in a pattern that resembles pages in a book. Damaged wood may also feel warm to the touch. Carton, or brittle, rounded structures made up of chewed wood, soil, and termite feces/saliva, is often present in voids.

Damage of Drywood Termite

Drywood termites usually infests dry wood and do not have a connection with the soil. They have been known to infest softwoods and hardwoods. Furniture, woodwork, and seasoned wood could be the target infestation for this species. Drywood termites will remove fecal pellets (or known as frass) from their feeding galleries and push out from the 'kick-out' holes. The 'kick-out' holes are usually 1-2 mm in diameter. Drywood termite fecal pellets are exist in sand-like form, hexagonal in cross-section, and can be a variety of colors, including whitish, red, or black. The fecal pellet may gather in piles or scatter around beneath the holes. 

Management of Subterranean Termite

• Use physical barriers, such as Basaltic Termite Barrier (BTB), Termimesh, or steel-beam construction. BTBs are particles of a specific size that are too large for termites to move and are not able to be tunneled through by termites. BTB must be placed unbroken and uncontaminated (e.g., surrounding soil, gravel, etc.) under concrete slab to be effective, and is often required for new construction. Different species require different particle sizes; however, in Hawaii, the size used is for the Formosan and Asian subterranean termites. Termimesh is woven stainless steel mesh that termites cannot pass through or chew through. This material is often seen covering the bottoms of telephone poles. Termimesh may be applied to pipes, cold joints, and foundations, as well as areas vulnerable to termite attack.
• Ensure the structure is clear around the perimeter so any mud tubes may be seen. Remove any wood to soil contact. Remove lumber, cardboard, paper products, and plant debris quickly. Ensure no excess water is present on wood or within a few feet of the home. Fix leaks as soon as possible. Make sure gutters drain away from the home and do not put plants or sprinklers close to the house. Check for pooling of water or poor drainage. Ensure the concrete is not cracked. Turn off lights during swarms. Get a professional inspection when necessary.
• The conventional method of subterranean termite control was the use of soil insecticides placed under the structure as a barrier. Repellent termiticides act as deterrents, while non-repellent termiticides aim to kill termites after contact. Large amounts of chemical must be applied, and these chemicals may have non-target effects. However, subterranean termites may find paths to the structure if there are gaps in the application. Further, only a portion of the subterranean termite colony actually comes into contact with the termiticide while the rest of the colony continues to live and pose danger to the structure. Termite baiting systems can eliminate colonies, while liquid termiticides usually only cause localized termite exclusion.
  
• Bait systems were developed to eliminate the entire colony by providing a chitin synthesis inhibitor (CSI) in stations around a structure; these stations allow workers to feed on the bait and then feed the bait to the rest of the colony. The CSI interferes with the termites’ ability to molt, so the workers die at a later time (workers may take ~45 days to molt). Eventually, the workforce dies and the colony collapses. Traditional bait systems do require regular monitoring by pest control operators. Durable baits are long-lasting and always active. Cellulose matrices are used in baits to specifically target termites.

Management of Drywood Termite

• Wood treated with preservatives should be used in building construction to prevent termite attack, especially in areas with high termite infestations.
• Spot treatment involves spraying or foam application of insecticides injected into the infested wood galleries.
  
• Fumigation or tenting is recommended for severe or widespread infestations. Fumigant gas will be released and circulated throughout the tented home so that the fumigant gas will reach the termite and kill them. Fumigation is a process involves restricted used pesticides and must be performed by certified professionals. Homeowners and pets need to leave the home during the fumigation process which normally takes about 1 to 3 days.
• Heat treatment is another way to control termite infestation. Compared to fumigation, heat treatment is non-chemical and non-toxic. Heat will be introduced into the infested home to raise the air temperature to between 120 F and 140 F. However, both fumigation and heat treatment are more reliable and effective in eradicating drywood termite infestation where they usually have relatively smaller colonies and restricted infestation areas. For subterranean termite infestation, baiting or soil treatment can be performed to achieve complete colony elimination.

References

• Urban Insects and Arachnids: A Handbook of Urban Entomology (2005). William H Robinson. Cambridge University Press.
• Urban Pest Control in Australia (1985). P Hadlington and J Gerozisis. New South Wales University Press.
• NPMA Field Guide to Structural Pests, Second Edition (2007). Eric H. Smith and Richard C. Whitman.