- 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: 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: Casey Hubble
[Originally published in the Summer 2022 issue of the UC IPM Green Bulletin]
The three-lined cockroach, Luridiblatta trivittata, (Figure 1) is the smallest cockroach species in California, with adults averaging only 5–7 mm in length. This newly introduced cockroach is native to North Africa and the Eastern Mediterranean. It was first detected in California around 2004 in Marin County, but it was not positively identified until 2009. Since then the three-lined cockroachhas slowly expanded its range to include the entire San Francisco Bay Area, south to San Luis Obispo, east to the foothills of El Dorado County, and north to Mendocino County.
Life cycle and biology
The three-lined cockroach lives in some of the most densely populated parts of northern California, but it's not a domestic pest species since it is rarely found indoors. Instead, these cockroaches prefer to live outdoors in natural or ornamental landscapes and can be found in matted thatch, compost bins, and leaf litter. Occasionally in late summer and early fall, adults will wander indoors through poorly sealed exterior doors and windows.
When inside, they are often misidentified as German cockroach nymphs (Blattella germanica), sometimes leading to unnecessary indoor insecticide applications. However, the number of stripes on the cockroach's body can help distinguish the species. The three-lined cockroach has three distinct stripes that run down the length of the adult's body, while German cockroach adults and nymphs have only two stripes (Figure 2).
It is unclear what the three-lined cockroach likes to eat in the landscape. Within the San Francisco Bay Area, this species has been observed feeding on the juices from overripe fruit in trees, and various food scraps from compost bins. Though these food items may be delicious treats for the cockroaches, they would appear to be atypical meals, since large populations of this insect have been found far from fruit or human food resources. Though scant, existing scientific literature classifies them as detritivores (organisms that feed on decaying organic material, especially plant matter), but it is unclear exactly what kinds of detritus might be preferred. Unfortunately, this question remains a mystery, since insect field diets can be notoriously difficult to determine.
Virtually no research has been conducted on this species, even in its native range. To better understand the biology and ecology of L. trivittata in California, the SF Bay Area Urban IPM Team launched a field study and several lab studies in 2021, revealing some interesting observations:
- Three-lined cockroaches have only one generation per year (Figure 3).
- Juveniles hatch in mid-April and develop through spring and early summer, eventually maturing into adults during July and August.
- Once mature, females lay egg cases (called oothecae) that will overwinter until next spring. Oothecae start out mint green in color, and as they develop, turn from olive green to dark brown before they are deposited into the landscape (Figure 4).
Mediterranean climates with long dry summers and short wet winters, found in California as well as their native habitat, seem to be ideal for this species. Juveniles do not seem able to hatch from their oothecae without some spring precipitation. On the other hand, too much water throughout the overwintering cycle may cause the eggs to mold, killing the nymphs before they can hatch. Females lay on average two or three oothecae per year. Each ootheca is very small (2 mm in length) and contains about 10 tiny cockroaches on average. This number is smaller than that observed for other outdoor cockroach species in California, where most average between 11-21 nymphs per ootheca.
The common name “three-lined cockroach” was suggested by the SF Bay Area Urban IPM team and officially adopted by the Entomological Society of America. This name is not only an accurate description of the insect's appearance but is also reflected in the scientific name Luridiblatta trivittata.
What can you do?
Proper identification is crucial to providing effective pest control services. While the three-lined cockroach prefers to live outside (only occasionally wandering indoors), the German cockroach lives exclusively indoors and is considered a major public health pest. Signs of the three-lined cockroach indoors may signal the need for better structural exclusion while German cockroach infestations will need immediate remediation. If you are unsure of the pest species, contact your county's UC Cooperative Extension office, Department of Agriculture, or Vector Control District for confirmation.
Though the three-lined cockroach may be considered a nuisance pest when found in large numbers, it may not ever call for control measures. There are many unknowns remaining about this species, such as how far it may expand throughout California and neighboring states. To help us track the spread of the three-lined cockroach, you can submit photos and report sightings to iNaturalist (https://www.inaturalist.org/) or BugGuide (https://bugguide.net/node/view/15740); these civic science data can be pooled to create distribution maps (Figure 5).
This research was funded by the California Department of Pesticide Regulation.
California Plant Pest & Disease Report Vol. 25. 2009. CDFA
Sutherland AM, Choe D-H, Rust MK. 2019. UC IPM Pest Notes: Cockroaches. UC ANR Publication 7467. Oakland, CA.
Djernæs, Marie, et al. "Phylogeny and life history evolution of Blaberoidea (Blattodea)." Arthropod Systematics & Phylogeny 78.1 (2020): 29-67./h2>/h2>/h2>/span>
- 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>