- Author: Andrew M Sutherland
Subterranean termites (Family Rhinotermitidae) are considered the most serious wood-destroying pests in the world, causing an estimated $32 billion in global economic impact each year. California is home to both native and introduced subterranean termite species (Figure 1). Infestations of wooden structures are widespread and common. Pest control operators (PCOs) have conventionally applied liquid termiticides to control these pests, usually as soil drenches or injections around structures. These treatments may not always be effective, however, especially if good underground coverage is not achieved, if local termite pressure is very high, or if dealing with the invasive Formosan subterranean termite in Southern California. Furthermore, the active ingredients in most liquid termiticides are increasingly monitored by the State as environmental contaminants and may be subject to legal restrictions in the future.
Bait systems for subterranean termites (Figure 2), which employ slow-acting insecticides that kill worker termites by preventing successful molting, may represent effective alternatives to liquid treatments. Baits, deployed within stations installed in the ground or in line with aboveground shelter tubes, have gained popularity during recent decades and are now considered the primary subterranean termite control tactics in many parts of the world. Adoption of bait systems in California has lagged most other regions, however. Reasons PCOs in California have reported being reluctant to use bait systems include 1) time required to achieve control is too long, 2) little efficacy data in California, and 3) the regular monitoring of bait systems is too labor intensive or otherwise does not fit established business models.
Recently, the third “adoption barrier” may have become less important: new product label guidelines allow PCOs to extend inspection intervals up to 12 months and allow for baiting without the previously required monitoring phase (provided the target pest is confirmed at the site). Considering the regular revenue streams created by “controlled service agreements”, where PCOs contract with property owners to prevent and control pests over a long term, these newer labels should drive more widespread use.
Some observations and case studies indicate that, indeed, bait system adoption is now slowly increasing in California. To address the other two reported barriers (speed of control and efficacy), we secured funds from the state's Structural Pest Control Board to evaluate and demonstrate three different in-ground bait systems in the San Francisco Bay Area and the greater Los Angeles area.
Our first objective was to evaluate efficacy at single-family homes. To do this, we collaborated with five different PCO companies who expressed interest in the new business models made possible by the newer bait product labeling guidelines. Some of these companies had experience with baits, while some gained their first experiences through this project. Companies received research stipends to subsidize their participation. Fifteen single-family homes were eventually selected, based on several experimental criteria: 1) documented activity of subterranean termites within 1 meter of the structure, 2) no liquid termiticide application within the previous 5 years, and 3) no significant structural infestations detected during the initial inspection. Participating homes were in Alameda, Contra Costa, Los Angeles, Orange, and Santa Clara counties. Bait stations, baits, service equipment, and, in some cases, training, were provided by manufacturers.
The UC research team and the PCOs installed bait systems according to product labels, usually with one bait station for every 10–20 linear feet of the structural perimeter. Since all 15 sites had confirmed termite activity at the perimeter, all stations installed contained active bait, rather than monitors. The UC research team installed monitoring stations with wooden blocks immediately adjacent to each bait station. The UC team then visited each participating home every 3 months for 2 years, checking termite activity within monitoring stations and collecting termites whenever possible. The PCOs and the UC team visited each participating home every 6 months to check termite activity within bait stations, replenish baits (as per product label), and to collect termites. Collected termite specimens were sent to a collaborating lab for DNA analysis, where each sample was assigned a “Colony ID” based on its genetic signature, distinguishing it from all other colonies. At the end of the 2-year period, a final structural inspection was conducted at each home.
Most importantly, despite significant termite pressure, none of the 15 homes became infested during the study period. Foraging termites were observed and collected during initial inspections, from wood blocks during quarterly inspections, and from bait matrices during bi-annual inspections with PCOs. In some cases, termites were observed and collected from bait stations only 6 months after installation. 132 separate samples of western subterranean termites (Reticulitermes hesperus species complex) were collected. DNA analysis revealed that many of our research sites included between 3 and 5 unique colonies; 1 property included 15 unique colonies! Bait was consumed at all sites, to varying degrees. No termite colony recovered from bait stations was ever detected again.
These observations strongly suggest that all three studied bait systems were effective at eliminating termite colonies and at preventing structural infestations over a 2-year period. Furthermore, post-project surveys conducted with property owners and PCOs indicated that all parties were satisfied with the services provided and control achieved; several companies new to baiting have now embraced the program we demonstrated as a new service offering for their customers.
Our second objective in this research project was to investigate factors influencing bait interception time (also called “time-to-attack”). One explanation for lengthy bait interception times in California may be the interaction of climate (hot summers with little to no rain) and soil texture (high proportions of clay). Termite foraging at or near the soil surface may be limited or even nonexistent during summer months, especially when areas are not irrigated. Some research supports this idea: western subterranean termites have been observed to forage near the surface mostly during winter months in Southern California. This suggests that baits installed in summer may sit uninvestigated for 6 months or more. To test this hypothesis, we established five research plots at the UC Berkeley Richmond Field Station directly on top of areas where naturally occurring Reticulitermes termites had been observed or collected. Around these areas, we established 3 concentric rings of bait stations at 3 distances from the center, installing 1 station from each of 3 registered systems (Table 1) along each of the 3 distance rings at the beginning of each season over 1 year, for a total of 36 bait stations per plot. We didn't want to kill the termites in these plots because that would significantly confound our data, so we used cellulose bait matrices from manufacturers that did not contain the active ingredients. We also installed monitoring stations containing wood blocks at the center of each plot and along each of the three distance rings. We then checked each station every 2 months for 2 years, recording bait consumption and termite incidence.
Of the 180 bait stations and 20 monitoring stations installed, 78 bait stations and 9 monitoring stations had been hit by the end of the 2-year project period, representing an overall hit rate of 44%. Three stations were attacked within 60 days after installation, and 10 stations were attacked within 120 days. Overall, however, the average bait interception time was 367 days, supporting the general claims of California's pest control operators that baiting may take too long for most remedial termite control jobs. There were no significant differences between the three bait systems or the three distance rings.
Bait System, Manufacturer
Installation Specifications (for in-ground use)
Sentricon Always Active, Corteva Agriscience
Recruit HD Termite Bait (EPA# 62719-608): cellulose tube, 0.5% noviflumuron
≤ 20 feet intervals; buildings, fences, decking, utility poles, trees
Inspections at least once annually; replace bait if damaged or ≥ 1/3 consumed
Advance Termite Bait System (ATBS), BASF
Trelona Compressed Termite Bait (EPA# 499-557): cellulose wafers in plastic housing, 0.5% novaluron
≤ 20 feet intervals; buildings, trees, wood piles, landscape elements, railroads
Inspections at least once annually; replace bait if damaged or ≥ ½ consumed
Exterra Termite Baiting System, Ensystex
Isopthor Termite Bait (EPA# 68850-2): cellulose wafers within burlap sachet, 0.25% diflubenzuron
≤ 20 feet intervals; buildings and other structures
Inspections every 45 – 120 d, up to six months allowed; replace bait “after sufficient consumption”
Our study's main question was whether installation season significantly impacts “time-to-attack” due to seasonal differences in termite foraging in California. To answer this, we pooled data from all five sites and all three bait systems and then considered just the first year of observations. The result was clear: baits installed at the beginning of winter (December 16) were intercepted ~100 days faster than baits installed at the beginning of summer (June 24)!
Bait stations systems may be very useful pest control tactics for use against subterranean termites in California, especially when dealing with very large colonies of native western subterranean termites, multiple colonies, sensitive sites, or sites where liquid treatments have failed. According to the labels of the three products evaluated, systems can be installed with active ingredients present on Day 1, provided a licensed Field Representative has detected and identified the target species at the site. Licensed Applicators may, according to label language and California's Structural Pest Control Act, then service bait stations, replenishing bait that has been consumed or damaged. Two of the systems evaluated allow for annual inspections, while one allows for bi-annual (every 6 months) inspections. Operators in California may decrease the bait interception time, and therefore the perceived early efficacy, by targeting initial installations for the beginning of the wet season.
The Formosan subterranean termite (FST), Coptotermes formosanus, is a very destructive pest first reported in California in 1992 in La Mesa, San Diego County. FST has since been found in Canyon Lake, Riverside County, Rancho Santa Fe (San Diego County) and Highland Park (Los Angeles County).
While this termite species is currently only found in a few locations in Southern California, it's important for residents and professional pest managers to be aware of them. Wood destroying pests can easily be moved through human activities.
To identify Formosan termites, UC IPM advisor Dr. Siavash Taravati and Dr. Chow-Yang Lee of UC Riverside developed this poster. Email them at email@example.com or firstname.lastname@example.org if you see any termites resembling those in the poster.
For Pest Management Professionals: Is the management for Formosan termites the same as management for native subterranean termites?
The short answer is “it depends!”. Formosan subterranean termites (FST) can form extremely large colonies in the field reaching millions of individuals. When the active nests are primarily in the ground, most colony members stay in the ground except when foraging for food. In this case, in-ground baiting is used against native subterranean termites and it may provide adequate control. However, some FST colonies could be formed above the ground (aerial) with no or limited contact with the soil. In-ground baiting is unlikely to be effective for managing such aerial colonies.
If you are a structural PMP, read more in the Spring 2023 Green Bulletin Newsletter.
To learn more about subterranean termites and their management, see Pest Notes: Subterranean and Other Termites.
- Author: Help Desk Team
For most of the Bay Area we had an unexpected but wonderful seasonal surprise – RAIN. This blessing provided a drink of water to plants that we have had to ignore due to water rationing.
We were not the only ones waiting for that first seasonal rain. Subterranean termites were waiting for that cue to emerge from the soil and party. Winged reproductives leave the underground nest in swarms to seek out a mate and then search for a new nest site. You may have seen them flying in swarms or on the ground exiting or landing on the soil.
They generally fly less than 300 feet from their emergence point. Their goal may be thwarted though, as this ritual exposes them to predation by birds, reptiles, spiders, and other insects. Most of the reproductives don't survive the feeding frenzy.
The most common subterranean termites, Reticulitermes, can be encountered in nearly all regions of the state. It can swarm in fall or spring and both situations are warm days following rain. They are not very big, less than one-half inch long including the wings, which are silvery-gray and twice the length of the body itself.
When not involved in the mating ritual, they live in the soil. Subterranean termites require a moist environment, and living in the soil and feeding in dead and decaying wood meets that need.
Termites are decomposers which benefit the environment. Unfortunately for us, dead wood includes structural lumber of which our homes or outdoor structures are made.
Since most soil around a home has buried wood debris (roots, stumps, or fence posts), finding swarming termites in your yard doesn't necessarily mean your house is infested. If you see a swarm on your property, do you have a problem? Possibly.
Andrew Sutherland, University of California's Urban Integrated Pest Management Advisor for the Bay Area, wrote in his blog: “If observing a swarm on your property, especially if near your home or other structures, you can hire a professional termite company for a detailed inspection. Make sure to photograph or otherwise note the swarm location so that the inspector can start there.”
If you would like additional information on subterranean termites, including recognizing their activity in and around the home and management options, check out the following link to UC IPM's Pest Note titled Subterranean and Other Termites.
Help Desk of University of California Master Gardener Program of Contra Costa County (EDC)
- Author: Andrew Mason Sutherland
It's that time of year again: termite swarm season! Western subterranean termites, Reticulitermes hesperus (species complex), produce reproductive swarms during calm sunny periods immediately following the first autumn rains. This is especially pronounced in the San Francisco Bay Area and parts of the Sacramento Valley, where mature termite colonies across a broad region may swarm simultaneously en masse, filling the air with termites fluttering their gossamer wings and filling social media discussions with wonder, horror, confusion, and dread.
What should you do? If observing a swarm on your property, especially if near your home or other structures, you can hire a professional termite company for a detailed inspection. Make sure to photograph or otherwise note the swarm location so that the inspector can start there. Even if you don't see swarms on your property, regular (every three to five years) inspections will help detect infestations before they cause significant damage and prevent future infestations. There are several proven management strategies for termites; review UC IPM's Pest Notes: Subterranean Termites.
For now, perhaps we can all appreciate the wonder of this natural spectacle. Winged termites are great sources of food for birds, lizards, other insects, and spiders. Termites also provide important ecosystem services, such as decomposition of wood and fallen leaves, contribution to soil structure formation, enhancement of water infiltration in soil, and facilitation of nutrient availability to plants. Furthermore, western subterranean termites are native to California and have been here long before we built wooden structures on top of their colonies. (Termite) love is in the air!/div>
- Author: Kathy Keatley Garvey
Lewis will cover the life and legacy of African-American entomologist and civil rights advocate Margaret Collins (1922-1996) at his presentation on Tuesday morning, Nov. 2. The long-awaited conference will be hybrid, that is, both virtual and in-person.
Collins will be "the fourth woman and second Black entomologist to be the subject of the Founders' Memorial lecture in the award's 64-year history," according to an ESA news release. (See list of previous recipients.)
'The Termite Man'
Vernard Lewis, who holds a doctorate in entomology (1989) from UC Berkeley, is a recognized national and international authority on drywood termites. He is known for his pioneering research on detection innovations and nonchemical methods of control. Lewis joined the UC Berkeley faculty in 1990 and was the university's first African-American faculty-member hired in the 150-year history of the Rausser College of Natural Resources. He retired July 1, 2017 from a 35-year career as an urban entomologist, the last 26 years as a Cooperative Extension specialist. As Lynn Kimsey, director of the UC Davis Bohart Museum of Entomology and UC Davis distinguished professor of entomology told us in a Bug Squad blog in July 2017: "He was the best; knowledgeable, personable and engaged. I'm really annoyed that he retired."
"He was always the go-to person in Extension when it came to termites, and he had that special personality which enabled him to immediately engage with people," related UC Davis distinguished professor Frank Zalom, a past president of the 7000-member ESA. "I always got the feeling that he genuinely liked what he did, and it showed."
During his career, Lewis focused his research on a variety of urban pests, including not only termites, but ants, bed bugs, cockroaches and wood-boring insects. He authored more than 150 refereed and trade magazine articles and book chapters on termites and other household insect pests. He delivered more than 700 presentations to widespread audiences. Lewis was inducted into the National Pest Management Association Hall of Fame in 2016. Since achieving emeritus, he has been spending his time on university and industry committees and public boards dedicated to increasing diversity, equity, and inclusion for underrepresented minorities and women into STEM careers.
In June 2020, Brite Energy Innovators paid tribute to Lewis as one of the world's Amazing Black Scientists. An excerpt: "At UC Berkeley, Lewis famously constructed a 400-square-foot (37-square-meter) wooden building near the campus for investigating pest insect detection and control; The structure was affectionately known as 'Villa Termiti.' Built in 1993, the building temporarily housed rotating communities of bedbugs, termites, beetles and ants, while Lewis and other scientists studied the insects' habits and tested their resistance to different methods of extermination. These included exposure to X-rays, microwaves, liquid nitrogen and fumigation, according to UC Berkeley."
Another excerpt from Amazing Black Scientists: "Lewis also worked to promote diversity in entomology, and participated in outreach programs to introduce underserved youth to life sciences, insects and biodiversity." He was one of 20 researchers featured in ESA's 2015 book “Memoirs of Black Entomologists,” designed to encourage minority students to pursue careers in science.
Margaret James Strickland Collins was known as "The Termite Lady" during her entomological career that spanned five decades. She engaged in extensive research on termites that included identifying a new species, Neotermes luykxi. "Her pioneering studies on the mechanism and evolution of termite desiccation resistance across various habitats provided foundational knowledge for generations of entomologists, field biologists, and ecologists," said Lewis, who wrote about her in a piece published June 1, 2016 in BioOne journal.
His abstract: "Often legends go unrecognized for their achievements in science and the betterment of society. In the case of Margaret Collins, it has been almost 20 years since her passing, and except for appreciation by a small cadre of termite experts, her contributions to entomology have received scant notice. However, her work and legacy have stood the test of time, and even today, she is considered, and often cited as, the definitive source for differences in toleration and resistance to drying among species of termites. At her core, Margaret was a field biologist, and she demonstrated it through her travels and termite collection trips to a dozen countries. Her long and illustrious career included publishing of scientific papers, tenured faculty positions, and service as a curator of the termite collection at the National Museum of Natural History, Smithsonian Institution, in Washington, District of Columbia. Margaret achieved many firsts during her life. She was the first African American female to be awarded a Ph.D. involving entomology at a major university. In addition, she was the first woman graduate student for the legendary isopterist and Professor of Zoology, Alfred E. Emerson. Her passion for termites remains highly visible in her published works. Her passion for her family and her strong support of civil rights for women and African Americans were less visible except to those she knew personally."'
Born in Institute, W.Va., on Sept. 4, 1922, Margaret was recognized as a child prodigy at age 6, "as evidenced by her being awarded the privilege to check out books at the West Virginia State College Library," Lewis wrote in the journal article. Following her high school graduation at age 14, she went on to receive her bachelor's degree in biology from West Virginia State College in 1943, and her doctorate in zoology in 1949 from the University of Chicago. Her thesis: Differences in Toleration of Drying among Species of Termites (Reticulitermes).
Collins was one of the first African-American women to receive an advanced degree related to zoology/entomology. "Those of us with collegiate degrees are well aware of the challenges and obstacles that can drain enthusiasm and delay completion, which include lack of funding, being away from home, and difficult and demanding courses and class loads," Lewis wrote. "Margaret had all of these, plus more."
"Upon receiving her Ph.D. in 1950 at the University of Chicago, Collins became the first African-American female entomologist," Lewis noted. "In the mid-'50s while on the faculty of Florida A&M, her invitation to speak at a local predominantly white university on biology and equity was cancelled due to a bomb threat. During the Florida A&M Student Council bus boycott of 1955 to protest racial inequality, Dr. Collins volunteered to drive people to work. These activities led to her being closely watched by the police and FBI."
In 1979, Collins coordinated an American Association for the Advancement of Science symposium on "Science and the Question of Human Equality," and later that year, published a book with the same title. The book is "an interdisciplinary look at racism and science, investigating the biological and social realities of individual and group differences," according to the publisher.
Love of Science
Just like Margaret Collins, Lewis shares a love of termites, a love of science, and a love of public service. In the ESA news release, ESA President Michelle S. Smith praised Lewis for his "remarkable career in both research and extension" and as "a role model for current and future generations of insect scientists. His pioneering spirit echoes that of Dr. Margaret Collins, and her story of determination, curiosity, and perseverance will be a perfect complement to our annual meeting showcasing adaptation and transformation in insect science."
The ESA meeting is appropriately themed "Adapt. Advance. Transform."
Yes! "Adapt. Advance. Transform." And let's add one more: "Recognize!"
We're delighted to see this much deserved recognition for two legendary entomologists.