- 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.
Some pest problems can be easily handled at home yourself. But if your pest issue is a bit more serious, or you don't have the time or tools to address it yourself, hiring a pest control company might be your best option. Pest management professionals are trained in pest control regulations and methods as well as the principles of integrated pest management (IPM). They can accurately identify your pest and get rid of the problem safely and effectively. While their services may seem costly, the investment can actually save you time and money in the long term.
Before hiring a pest control company, try to do some research on your suspected pest and its management. Consult the UC IPM Pest Notes for help with identification and management to see what control options are available. When you contact a pest control company, prepare yourself to ask about these options and whether they provide IPM services like monitoring, pest exclusion, baiting, trapping, and reduced-risk (less toxic) pesticides.
For detailed steps and questions to ask when hiring a pest control company, consult the newly revised Pest Notes: Hiring a Pest Control Company authored by UC IPM advisors Siavash Taravati, Andrew Sutherland, and UCCE advisor Darren Haver.
- Author: Mike Hsu
During summer swarming season, homeowners urged to check for signs of Formosan subterranean termite
In the lottery of troublesome termite infestations, “Roger,” a Rancho Santa Fe homeowner, hit the jackpot (a pseudonym is used to protect his privacy). In 2021, his house in San Diego County was identified as home to only the fourth documented colony of the Formosan subterranean termite (Coptotermes formosanus) in California.
“FST is one of the most destructive urban pests in the world,” said University of California, Riverside entomologist Chow-Yang Lee, affiliated with UC Agriculture and Natural Resources through the campus' Agricultural Experiment Station. “It's also the only termite species listed in the ‘100 of the World's Worst Invasive Alien Species.'”
Endemic to East Asia, this termite is now established in many tropical and subtropical regions, including across the American South. Annually, its infestation costs more than $4 billion in control measures and damage repairs of structures in the U.S.
FST was first discovered in California in La Mesa (San Diego County) in 1992, and it was rediscovered in that city in 2018. Another infestation was reported in Canyon Lake (Riverside County) in 2020. And then, the following year, Roger received his surprise.
“Imagine being in your kitchen looking at your drywall and it's totally normal and then the next day there's a four-inch hole there and you're like ‘What the heck is that? Who put their elbow into the drywall?'” he recalled.
FST colonies can reach millions of individuals
Roger hired a pest control company, Green Flash Pest Control, which sprayed a powerful liquid termiticide in the soil around the house. But the termites – workers, soldiers and winged “alates” – continued to appear. The company tried a second application of soil treatment. But, again, the termites kept popping up.
“We were deeply concerned about the potential damage these termites could cause to the home since these invasive termites are extremely destructive,” said Eric Veronick, director of operations at Green Flash. “Unfortunately, there isn't a whole lot of information available on the behavior and management of this termite in California.”
“Some colonies are aerial, meaning that they are formed above the ground with limited or no connection to the soil – in such cases, soil treatment using contact insecticides may not be very effective in managing these termites,” Taravati said. “Furthermore, contact insecticides usually kill a much smaller portion of the colony when compared to termite baits.”
To make matters worse, once FST is established in an area, there have been no records of successful eradication anywhere in the world, according to Taravati. He added that a major reason why the Formosan subterranean termite is so destructive is the enormous size of their colonies.
“Their colonies can reach millions of individuals, versus most native subterranean species that reach a few hundred thousand individual termites per colony,” Taravati explained.
This termite, through its sheer numbers, can turn the wood in a structure into a “spongy kind of cake,” in Taravati's words. More than 10 pounds of wood in a house can be eaten by a mature colony each month. The financial hit for a homeowner can be substantial, up to tens of thousands of dollars – not to mention the increased risks to safety.
“Anything from studs to rafters to door frames and window frames – everything is going to be compromised, if the termites are left unchecked. And then, as soon as we have a major stress on the building, let's say there's a big storm or an earthquake – there's a high risk of at least part of the building collapsing,” said Taravati, who also noted that, unlike California native subterranean termite species, FST can attack and kill live trees and plants.
“These termites can be a nightmare,” he said.
Summer is ‘swarming season' for FST
Since the Rancho Santa Fe case in 2021, four more colonies have been documented, in La Mesa again and also in Highland Park, Hollywood Hills and La Verne (the latter three in Los Angeles County). Taravati said it's possible that FST has been spreading via structural lumber or potted plants and soil.
And even if a colony appears to be eliminated at a certain locale, Taravati noted, there is always the chance that part of the colony survives or more colonies of termites already have been established in nearby locations, as a result of swarming termites from the originally infested property.
Although nominally “subterranean,” certain members of an FST colony grow wings and fly to nearby locations to establish new colonies. These winged alates are also called swarmers because of their behavior during the “swarming” season, when termites mate and reproduce.
For the Formosan subterranean termite, that swarming season in California is late May through early August, so now is the time for homeowners and building managers in southern and central California to keep an eye out for those winged termites.
“If you experience a termite swarm in your house, contact a pest management professional and keep some termite samples in a Ziploc bag in the event you need to send the samples to UC Riverside for morphological and DNA-based identifications,” said Lee, who added that it's a good idea to periodically check your structure for signs of infestation, such as wood damage or shelter tubes (mud tubes).
Lee said FST swarmers have a lighter colored body compared to the dark color of native subterranean termites and the orange-brown body of drywood termite swarmers (see this flyer for additional identification information).
Following an especially wet winter, there's a chance California could see more FST infestations, as this termite generally requires moist environments to thrive, Lee added. He recommends that concerned community members seek professional advice.
“Do not attempt to control an FST infestation by yourself,” Lee said. “This is not your typical native Californian subterranean termite species; they are highly destructive, and you want to intercept the problem with the right strategy before it's too late.”
Homeowner: ‘I owe them my house'
In Roger's case, Taravati enlisted the help of Lee and his UC colleague, Greg Kund. They made multiple visits to inspect the home and analyze the situation – going “above and beyond,” according to Roger.
At Lee's suggestion, they used a caulk gun to insert a gel-like experimental bait into the wall where the termites were coming out. Once spread and passed on to the other nestmates, the product – which contains a chitin synthesis inhibitor (a type of insect growth regulator) – interrupts the termites' development so they are unable to properly molt and replace the short-lived “workforce” of foragers and soldiers. The colony eventually collapses and is eliminated.
“Generally speaking, IGRs are much more effective, but they require more patience,” Taravati explained. “You're not going to see the results the next day, or two-three days. You're going to see the results in a few weeks – but when you see the results, it's massive.”
And that's exactly what Roger and Green Flash Pest Control saw.
“Soon after their bait application, the termites stopped emerging from the walls and that gave us and the homeowner a big sigh of relief,” Veronick said. “I appreciate their expertise and dedication in helping us get rid of this destructive pest."
Roger said he is immensely grateful to the UC team.
“They were fantastic; I owe them my house,” he said. “They were super gracious and helpful and responsive and – ultimately, the thing I care most about – they were effective; they fixed the problem. Here we are two years later and – knock on wood, or maybe I should knock on something else! – everything is good.”
Lee also credited Taravati for bringing his knowledge and “can-do” attitude to communities across Southern California.
“He is highly knowledgeable and always able to come up with feasible solutions,” Lee said. “We need good Cooperative Extension urban IPM advisors like Siavash who could provide good advice and bring solutions to the stakeholders, be they homeowners or pest management professionals.”
Taravati said community members need to maintain their vigilance and urges them to download and share the FST flyer that includes identification tips and contact information. He said they are always free to e-mail him with their concerns and photos of suspected FST – not only to help stop the spread of the pest but to expand scientific understanding.
“This termite is so new to California – even for us, as researchers. Despite being in La Mesa since the 1990s, it wasn't until 2020 when these termites were detected in other places, including Riverside and Los Angeles counties,” Taravati explained. “All of us need to learn more about this pest and closely monitor the behavior of this pest.”/h3>/h3>/h3>/h3>
- Author: Andrew M Sutherland
- Author: Brandon Kitagawa
Multi-unit housing (MUH), such as apartment complexes and single-room occupancy (SRO) buildings, can harbor significant infestations of cockroaches, bed bugs, rodents, and other pests. Structural continuity (shared walls of adjacent units), budgetary constraints, poor maintenance and infrastructure, and cultural and social factors allow pests to infest and thrive in these environments.
Many of these pests threaten public health and wellbeing of the residents. For instance, German cockroaches (Blattella germanica) produce proteins that can be found in their feces and exoskeletons that, when dispersed into the air, can be inhaled, causing asthma in children.
Pest management is often conducted in response to complaints or after discovery of serious problems rather than proactively, especially in low-income communities. Proactive integrated pest management (IPM) programs that include regular monitoring of pests within every residential unit improve building-wide pest control and prevent significant infestations. These programs are labor-intensive, however, especially at the onset, and so may be considered too expensive by property owners and managers.
To show the effectiveness of proactive IPM and to investigate the relationship between cost and pest control, we partnered with affordable housing providers to provide one-year “IPM interventions” at two MUH sites in the San Francisco Bay Area: a 75-unit SRO building in Contra Costa County and a 59-unit low-income apartment complex in Santa Clara County. This work was led by Regional Asthma Management and Prevention, a program of the Public Health Institute, and sponsored by the California Department of Pesticide Regulation.
IPM Intervention Methodology
We worked with the pest control operators already in contract with the housing providers at the two sites and revised existing contracts to include unit-by-unit monitoring. The project included funds used to offset the increased costs associated with these revisions. Operators were asked to design programs that included monitoring for cockroaches and bed bugs in every unit at least once annually. When pests were detected, management tactics would be selected according to the pest densities observed, with the overall goals of eliminating pest populations and reducing pesticide exposure. Typically, baits were used against cockroaches and desiccants, spot treatments, vacuums, and whole-room heat treatments were used against bed bugs.
Independently, our team of researchers assessed pest incidence and density at three points during the one-year interventions: before IPM protocols were in place (baseline), roughly six months afterward (midpoint), and about one year afterward (final). At each monitoring period, we placed one glue trap behind the refrigerator and one pitfall trap in contact with the bed or sleeping surface for periods of one to two weeks. We also trained management, staff, and tenants on pest awareness, prevention, and reporting. Monthly costs associated with the pest control programs were calculated, including contract values, supplemental or add-on service values, and on-site staff effort hours. These costs were compared to monthly costs before the proactive IPM interventions began. Finally, surveys and interviews were conducted with residents and staff at the study sites to measure their relative satisfaction with the proactive IPM programs. Access to residential units required written notices delivered 24 hours before intended entry and accompaniment by on-site staff.
Bed bugs (Figure 1) were the primary pests at the Contra Costa County site while German cockroaches (Figure 2) were the primary pests at the Santa Clara County site. Other pests present at these sites included small flies (of the families Psychodidae, Phoridae, and Drosophilidae), rodents, and stored-product pests like meal moths and grain beetles. Baseline assessments revealed that more than 20% of the units inspected in Santa Clara County were infested with German cockroaches and that about 10% of the units in Contra Costa County were infested with bed bugs.
High-density infestations were addressed first, with heat treatments for bed bugs and high-volume gel bait applications for cockroaches. Several of these high-density infestations were only discovered due to the unit-by-unit proactive monitoring process.
Many residents refused our team's entry, especially during the baseline assessment in Contra Costa County. Participation and compliance improved markedly after an on-site education program for residents.
By the intervention's midpoint, pest density at both sites began to decrease (Figure 3), though pest incidence was largely unchanged. Incidence apparently increased since access to several infested units was only achieved several months after the intervention's onset. In these cases, distrusting residents gradually learned about the project's goals and about IPM through the resident education programs and eventually granted the team access to their units. The final pest assessment at the end of the one-year intervention showed continued decreases in pest density but relatively unchanged pest incidence at both sites (Figure 3). This means that the severe infestations (dozens to hundreds of cockroaches or bed bugs per unit) had been significantly decreased or eliminated but that a similar proportion of units were infested as had been at the beginning of the project. This may be very important for building-wide IPM since pests can disperse from high-density units to new units, usually those units next to or otherwise structurally continuous with the severe infestations. Overall, the pest control under the proactive IPM program was considered significantly more effective than the reactive programs previously in place.
Contract base values for the proactive IPM services increased significantly at both sites when compared to the reactive pest control services previously in place (Table 1). However, when considering the supplemental costs associated with add-on services, usually bed bug heat treatments not covered by the base contracts, monthly pest control costs decreased at both sites under the IPM programs (Table 1). In fact, monthly costs decreased by almost $1,000 at the Contra Costa County site, where a severe bed bug problem had been ongoing for many years prior to this project.
Santa Clara County
Contra Costa County
monthly service costs under reactive program
$ 350 ($ 5.93 per unit)
$ 240 ($ 3.20 per unit)
annual supplementary costs under reactive program
$ 18,565 ($ 315 per unit)
$ 39,485 ($ 526 per unit)
total annual costs under reactive program
$ 22,765 ($ 385 per unit)
$ 42,365 ($ 565 per unit)
monthly service costs under IPM program
$ 450 ($ 7.63 per unit)
$ 360 ($ 4.80 per unit)
annual supplementary costs under IPM program
$ 16,044 ($ 272 per unit)
$ 26,924 ($ 359 per unit)
total annual costs under IPM program
$ 21,444($ 363 per unit)
$ 31,244 ($ 417 per unit)
Annual Savings from IPM Program
The majority of surveyed or interviewed residents (96% at the Contra Costa County site and 82% at the Santa Clara County site) reported being either “very satisfied” or “somewhat satisfied” with the pest management services being received, as compared with those in place before the intervention. About 87% of responding residents reported that they had received some educational materials about pests and IPM, and 93% of responding residents said that they would be likely to report pest sightings to management in the future. All staff interviewed reported that the IPM program was more effective, in their opinion, and that the unit-by-unit inspections allowed for more resident engagement surrounding pest control.
Overall, this project showed that proactive IPM programs that use regular unit-by-unit monitoring events can help detect unknown infestations, control severe infestations, reduce monthly costs, and satisfy on-site stakeholders. This result was somewhat unexpected, since IPM programs usually take more than one year to realize savings for MUH environments. In cases where expensive supplementary services, such as bed bug heat treatments, are common, however, savings under IPM programs may be realized very quickly.
- Author: Cheryl Reynolds
Are you in need of some last-minute CEUs for 2022? We're pleased to announce that a new online course on runoff and surface water protection is available and offered for free. If you are a pest management professional working primarily in structural pest control or landscape maintenance, then this course is for you! Developed by pest management experts from the California Department of Pesticide Regulation and the University of California, this course presents information on the Surface Water Protection Regulations that are found in Title 3 of the California Code of Regulations sections 6970 and 6972. These regulations were put into place to prevent pesticide runoff into California waterways and to reduce surface water contamination from pyrethroid insecticide use. In this course, you'll learn about the types of pesticide applications that are allowed under the regulations as well as application types that are prohibited and also application types that are exempt. The course takes a close look at pyrethroids, particularly bifenthrin because of its high use in urban areas, high detection in surface waters, and high toxicity to aquatic organisms. Fipronil, another commonly used ingredient in structural and landscape products, is addressed in the course as well because it has similar water-quality concerns as the pyrethroids. Specific label restrictions of bifenthrin and fipronil products in California are also discussed.
The Urban Pyrethroid and Fipronil Use: Runoff and Surface Water Protection course has been approved by DPR for a total of 1.5 continuing education units (CEUs), including 0.5 hour of Laws and Regulations and 1.0 hour of Other; and by the Structural Pest Control Board (SPCB) for 1.5 hours of Rules and Regulations.
UC IPM currently offers 22 other online courses with continuing education units from DPR. Many of our courses are also credited by the California Structural Pest Control Board (SPCB), Certified Crop Adviser (CCA), the Western Chapter of the International Society of Arboriculture (WCISA), and the Arizona Department of Agriculture.
In addition to our newest course, this year we are offering another course for free: Providing IPM Services in Schools and Child Care Settings.
Don't forget that if you are a license or certificate holder with the California Department of Pesticide Regulation (DPR) and your last name begins with the letters A through L, then this is your year to renew. DPR encourages all license holders to send in renewals as soon as possible. If you have specific questions about renewal with DPR, please see their new Licensing Renewal Information page.
Do you have general questions about our online courses and DPR and SPCB CEUs and want them answered live?
Join us on Zoom December 6. Drop in anytime between 3 and 4pm (PST).
Meeting ID: 984 3730 0331