Plant Pest Diagnostic Clinic (PPDC) at the Ohio State University (OSU) received this sample of termites in early April 2024 from Dayton, OH. The sample was of termite alates (winged stage), which usually have two pairs of equal-sized wings that they use to fly in large numbers, called a swarm (nuptial flight). We identified the species as Eastern subterranean termites, Reticulitermes flavipes, based on the dark coloration of the body, the time of the swarm, and the location. While wings are required for species identification, the sample collection data indicates that Eastern subterranean termite is the proper ID.
Eastern subterranean termite is the most common and widely distributed termite species in the continental United States. In Ohio, risk of subterranean termite infestation is rated as “moderate to heavy” (Beal et al. 1994).
The sample of termite alates received by PPDC was on a sticky trap.
The homeowner mentioned that he collected these specimens from his basement, where he suspected the kitchen sink as the route of entry. However, these insects cannot navigate through or survive in water. Unless the property had an inactive plumbing line with a broken pipe, the termites would be unable to use this point as the route of entry into the basement. It is more likely that these termites are infesting the client’s property and have created above-ground tunnels in the basement to release their swarm. Shown in the picture are male and female alates that have shed their wings. Upon landing, they lose their wings, find a mate, and find a suitable place to start a colony.
Taxonomy
Termites are grouped phylogenetically into two groups: 1) the lower termites (Families Mastotermitidae, Termopsidae, Hodotermitidae, Kalotermitidae, Serritermitidae, and Rhinotermitidae), and 2) the higher termites (Family Termitidae) (Kambhampati and Eggleton 2000). The lower termites utilize protozoan gut symbionts to digest cellulose whereas the higher termites lack symbiotic protozoans and rely solely on prokaryotic gut symbionts and endogenous cellulases (Bignell & Jones, 2009). The higher termites account for approximately 75% of all termite species in the world and have diverse feeding habits with some species feeding on fungi, soil, or cellulose materials (Krishna 1969).
Eastern subterranean termites are lower termites (Family Rhinotermitidae). Unlike higher termites, Eastern subterranean termites do not have defined nest territory. Their colonies consist of multiple infested food sources that are connected via underground tunnels. Each food source they inhabit is called a satellite nest, which may contain a neotenic reproductive. The colony is not territorial and moves based on food availability.
How many Reticulitermes species are in the United States?
Subterranean termites in the genus Reticulitermes are common structural pests in the Continental United States. According to Johnsosn and Forschler (2022), mapping of five Reticulitermes species has been identified (using molecular methods) in Georgea, representing eco-regions typical of most of the southeast and eastern seaboard of the United Staes. In this study, R. flavipes, R. nelsonae and R. virginicus were reported to be the most collected and widespread species in the region, while R. hageni and R. malletei were found predominantly north of the Fall line, that extends from Alabama to New Jersey along Appalachian mountain. R. hageni, is the least encountered species.
The southwestern United States, especially California and Arizona, is home to two native Reticulitermes species: R. hesperus and R. tibialis. A recent study conducted at the University of California using mitochondrial DNA (mtDNA) identified that R. hesperus consists of at least 3 reproductively isolated species and R. tibialis consists of at least 2, suggesting that 5 or more undescribed Reticulitermes species may be present in this region (Tseng et. Al., 2023).
Life Cycle and Biology
All species of termites have different castes, which include workers, soldiers, and reproductives. Each caste has specialized tasks and can be identified by their characteristics.
Usually in spring, a mature subterranean termite colony will produce and release winged alates as a mode for dispersal. The alates are characterized by their wings, well developed compound eyes, and fully pigmented bodies. Depending on species, fully hardened alates can be dark brown to black. Alates will swarm in large numbers, and an infested structures may see thousands of alates indoors during swarming seasons. After swarming, alates lose their wings, pair up, find a suitable place to start a colony, then mate. It is uncommon to see alates of subterranean termites during the winter, but warm areas around a building structure may rarely induce a winter swarm.
A pair that starts a new colony are called the ‘king’ and ‘queen’, which are the primary reproductives. Queen termites have greatly expanded abdomen during egg-laying seasons. Unlike ants, termite colonies have male reproductives, because female reproductives cannot store a large amount of sperm. Queen and king termites continuously mate to produce eggs and can live up to approximately 20 years. During the first few days, the queen lays its first batch of eggs, which is tended by both the king and queen. Eggs hatch into the pre-worker stage called the ‘larva’ (not true larva, since termites go through incomplete metamorphosis). Termite larvae are characterized by very pale bodies, lack of wing buds and eyes, and unpigmented mandibles.
The larvae molt into workers, which are larger, cream-colored, and have darkened mandibles. Majority of a colony consists of workers, which carry out various tasks, such as nursing, construction, and finding food sources. Workers can molt into different castes. Some workers will molt into soldiers, which defends the colony. Soldiers have enlarged and sclerotized head capsule and mandibles to aid in colony defense. Due to their large mandibles, soldiers are unable to feed alone and instead feed on regurgitations from workers. For mature colonies, some workers will molt into nymphs, which are the intermediate stage to becoming an alate. Nymphs can be identified by the presence of wing buds and slightly darker pigment than workers.
Life stages and castes of eastern subterranean termites.
Both workers and nymphs can also molt into secondary neotenic reproductives. Those that molt from nymphs are referred to as nymphoids, which have under-developed eyes and wing buds. Those that molt from workers are referred to as ergatoids, which lack eyes & wing buds and are smaller than nymphoids (Laine & Wright, 2003). Both are distinguishable from workers by their sight to heavy pigmentation. Neotenic reproductives are different from primary reproductives in that they only molt from nymphs and that they never develop wings. Neotenics are found in tandem with primary reproductives as supplementary egg producers. Therefore, a colony that loses its king and/or queen can continue to survive.
Different casts of Reticulitermes species
Signs of damage
There are various insects that infest wood in the United States, such as wood boring beetles, carpenter ants, and termites. Termites leave different signs of wood damage, which also varies by termite species. Pest control professionals use these signs and more to distinguish termite infestation from other wood-destroying organisms. Here, we focus on signs of damage caused by subterranean termites and other means to detect an infestation.
A swarming is the most common way a subterranean termite infestation is detected. In Ohio, Eastern subterranean termites swarm over spring and early summer. In infested homes, a swarm can result in up to tens-of-thousands of alates indoor. They often end up near windows or artificial light due to their attraction to light. Their shed wings on the ground are another sign that an active termite infestation is taking place in a building.
Termite alates are frequently confused with winged ants, and proper identification is necessary for proper control measures. With the exception of carpenter ants, other ant species generally do not damage wood. Alates of termites can be distinguished from ant alates by their straight antennae, similarly sized front and hind wings, and parallel waist sides. In contrast, ant alates have bent antennae, larger front wings than hind wings, and narrow waist.
Difference between winged ant vs winged termite alate.
Workers are very rarely found in open-air spaces and are usually undetectable. However, their activity can be seen through the construction of above-ground tunnels, called the mud tubes. These tubes are constructed using a mixture of soil, feces, saliva, and cellulose. Due to their soft bodies that are prone to desiccation, termite workers construct mud tubes to travel in open-air spaces. As subterranean termites require contact with the soil for moisture, mud tubes are frequently observed on outer walls and pillars close to the soil around infested buildings. These tunnels may also be seen near a swarm, as alates exit through a type of mud tubes called the swarm castle.
Mud tub or shelter tube of subterranean termites
Damaged wood is also a good indication of termite infestation. Wood damaged by subterranean termite are characterized by galleries that only go along with the grain of wood and the presence of dirt and fecal spots. A piece of wood may become completely hollowed when there is a heavy infestation. However, the external layer may be intact even for heavily damaged wood. If an infested wood piece is painted, search for lumps on the paint that may be indicative of termite activity.
Wood damage by subterranean termites
Subterranean termites are also capable of damaging non-wood items. These insects are known to damage soft items, such as leather, Styrofoam, etc, that are near the wood pieces they infest. On extremely rare occasions, they have the potential to damage food crops as well. Mississippi State University reported a small colony of eastern subterranean termites feeding on sweet potatoes in Mississippi in 2008. It is possible this is an accidental infestation due to the inability of the termite king and queen to find a suitable place to start a colony. Read More
Cultural and Chemical Control
Control of subterranean termites requires certified professionals, as proper inspection is necessary and effective chemicals are only permitted for licensed individuals.
The first step to control is inspection. This step includes proper identification and determining where termites are active. Great indications of a subterranean termite infestation include swarms (be sure not to confuse with ants), mud tubes, and damaged wood with characteristics mentioned above (gallery follow wood grain, fecal spots, dirt). However, the aforementioned signs of damage may not always be detectable. In such cases, moisture meter is a great inspection tool. Areas of infestation has elevated moisture levels due to termites’ ability to transport water. Moisture meter is also useful for determining where termites are present. Once an infestation verified, both cultural and chemical approaches are necessary for control and to prevent future infestation.
There are several cultural control measures that make a building less inhabitable for subterranean termites. The goals of cultural control are to remove access to wood and moisture. However, it should be noted that cultural control alone is not sufficient to remove an active subterranean termite infestation, but these measures are useful for preventing future infestations (Rust 2014).
To remove access to wood, we must first determine the route of entry. Any wood-to-soil contact gives termites direct access to wood within a building. Termites can also access wooden structures through cracks and crevice in the foundation and/or the walls. Lastly, excessive mulch pile placed near a building presents termites with indirect wood-to-soil contact. It is advised to remove any wood in contact with the soil (building structures, wood piles) and, if possible, to seal cracks and crevices. For mulch, keeping the level at least 6 inches below the foundation reduces accessibility to wood within a building and allows inspection space for mud tubes.
To remove access to moisture, homeowners/property managers must utilize proper water drainage system. These include pitched roof, proper downspout installation, clean gutter, drain tiles, and soil sloped away from foundation. In addition, keeping mulch level shallow (<2 in) helps to keeps the soil beneath dry. Good water management reduces the amount of water available for termites that can be transported to their nesting areas.
Chemical treatments are the primary methods for controlling subterranean termites. Two major means of chemical control are soil termiticide treatment and baits. Soil termiticides are applied around the perimeter of a building. Termites are exposed to the toxins while tunneling through treated soil. These chemicals can be either repellent or nonrepellent. The latter is more commonly used today, as termites are more likely to be exposed to the chemicals. Exposed termites not immediately killed, since non-repellent soil termiticides contain slow-acting toxins. The slow-acting nature of these chemicals allows the toxins to spread through a colony, once the exposed individuals return to their nestmates, die, and are consumed by their nestmates. One downside to soil termiticide is that soil shuffles naturally (i.e. root growth, animal activity, water flow), which will cause gaps in treated soil. In addition, soil termiticide use is restricted in buildings near bodies of water and sensitive environment.
Termite bait stations are arguably the most popular means to control subterranean termites today. Bait stations incorporate toxins into durable cellulose matrices, which termites consume. The toxins disrupt workers’ ability to molt properly and are slow acting. Similarly to non-repellent soil termiticides, the slow acting nature of termite baits allows toxins to spread through an infesting colony. Baits are installed around the building perimeter, approximately every 10 ft. Baits require much less chemicals for control and has reduced likeliness of run off. However, as bait stations require discovery by termites, pre-baiting using bait stations containing matrix without toxins may be necessary. Pre-baiting helps to lure termites to the desired location and to determine where termites are active.
This USDA 2022 termiticide report contains most of the USDA-approved chemicals.
List of EPA-approved baits and other chemicals to control termites
References
Allison Johnson and Brian T. Forschler, 2022. Biodiversity and Distribution of Reticulitermes in the Southeastern USA. Insects. 2022 Jul; 13(7): 565. Published online 2022 Jun 22. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9316241/
Beal, R. H., J. K. Mauldin, and S. C. Jones. 1994. Subterranean termites--their prevention and control in buildings. Home and Garden Bulletin No. 64 (revised), U.S. Department of Agriculture, Forest Service. Washington, DC. 36 p. https://www.fs.usda.gov/research/treesearch/26674
Bignell DE, Jones DT . 2009. A taxonomic index, with names of descriptive authorities of termite genera and species to accompany the book Termites: Evolution, Sociality, Symbioses, Ecology (Abe T, Bignell DE, Higashi M, editors, Dordrecht: Kluwer Academic Publishers, 2000) . Sociobiology 53 : 205 – 236 https://www.cabidigitallibrary.org/doi/full/10.5555/20093125166
Kambhampati S, Eggleton P . 2000. Taxonomy and phylogeny of termites. In: Abe T, Bignell DE, Higashi M, Editors . Termites: Evolution, Sociality, Symbioses, Ecology. pp. 1–23. Kluwer Academic Publishers . https://link.springer.com/chapter/10.1007/978-94-017-3223-9_1
Krishna, K. 1969. Introduction, pp 1-17. In Krishna, K, and F. M. Weesner [eds.]. Biology of termites. Academic Press, New York, NY. https://www.sciencedirect.com/book/9780123955296/biology-of-termites#book-info
Laine, L.V., & Wright, D.J., 2003. The life cycle of Reticulitermes spp. (Isoptera: Rhinotermitidae): what do we know? Department of Biological Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 7PY, UK. Bulletin of Entomological Research (2003) 93, 267–378. DOI: 10.1079/BER2003238. https://www.cambridge.org/core/journals/bulletin-of-entomological-research/article/abs/life-cycle-of-reticulitermes-spp-isoptera-rhinotermitidae-what-do-we-know/C7155340AE7D2481CAF1D928FC045DBF
Rust, 2014. management strategies for subterranean termites. https://books.google.com/books?hl=en&lr=&id=zlDNBAAAQBAJ&oi=fnd&pg=PA114&dq=eastern+subterranean+termite+life+cycle&ots=fG1mG1JBR4&sig=41GW76hYUPUYDBnNY_BNrjsRkxM#v=onepage&q&f=false
Shu-Ping Tseng, Lori J Nelson, Casey W Hubble, Andrew M Sutherland, Michael I Haverty, Chow-Yang Lee. 2023. Phylogenetic analyses of Reticulitermes (Blattodea: Rhinotermitidae) from California and other western states: multiple genes confirm undescribed species identified by cuticular hydrocarbons, Journal of Economic Entomology, Volume 116, Issue 6, December 2023, Pages 2135–2145, https://doi.org/10.1093/jee/toad182
Throne, B. L., J.F.A. Traniello, E.S. Adams and M. Bulmer. 1999. Reproductive dynamics and colony structure of subterranean termites of the genus Reticulitermes(Isoptera Rhinotermitidae): a review of the evidence from behavioral, ecological, and genetic studies. Ethology Ecology & Evolution 11: 149-169, 1999. https://www.tandfonline.com/doi/abs/10.1080/08927014.1999.9522833
Types of termites in FL - https://flrec.ifas.ufl.edu/termites-in-florida/termite-types/
