After the Rodenticide Ban, Ten Licences Make Two Thirds of Use
Key result: Two years after California restricted second-generation anticoagulant rodenticides, 660 pest control licences still reported using them in 2023, but 10 made 66.2 percent of those applications. In Merced, Tulare and Stanislaus counties the restricted compounds were still 40 to 49 percent of structural rodent baiting, against 1.8 percent in San Diego.
What the ban left behind
Our analysis of California’s rodenticide restriction found that structural applications of brodifacoum, bromadiolone, difenacoum and difethialone fell 85 percent in 2021, the first year of AB 1788, and that 263,926 applications remained in 2023. The law allows that remainder: it exempts public health and vector control work, water infrastructure, and “agricultural activities”, which it defines to include food warehouses, slaughterhouses, canneries, factories, breweries and wineries.
The statewide total does not say where the remaining use happens or who does it. California’s pesticide use reports do, by county and by reporting licence. We extracted every structural rodenticide application in 2022 and 2023 by county, compound and licence.
Where the restricted compounds are still used
| County | Second-generation applications, 2023 | Share of the state’s | Share of the county’s rodenticide applications |
|---|---|---|---|
| Los Angeles | 54,514 | 20.7% | 7.9% |
| San Bernardino | 23,207 | 8.8% | 15.0% |
| Orange | 19,212 | 7.3% | 6.7% |
| Fresno | 17,000 | 6.4% | 32.9% |
| Stanislaus | 12,417 | 4.7% | 39.7% |
| Tulare | 11,880 | 4.5% | 44.6% |
| Riverside | 10,937 | 4.1% | 4.4% |
| Ventura | 10,135 | 3.8% | 12.5% |
| Merced | 9,859 | 3.7% | 48.6% |
| San Diego | 8,468 | 3.2% | 1.8% |
| California | 263,926 | 100% | 8.7% |
Source: California Department of Pesticide Regulation, Pesticide Use Report 2023, site code 10, application counts by county of use. Ten counties with the most second-generation applications. All 58 counties in the CSV. Author calculation.
What it means. In absolute numbers the remaining use follows population, led by Los Angeles. As a share of rodent work it follows a different map. Across the San Joaquin Valley, a third to a half of structural rodenticide applications still use the restricted compounds; along the southern coast, under a tenth. The exemption list, with its food warehouses, processing plants and wineries, is one plausible reason, since the valley has many such facilities, but the use reports do not record which exemption applied, so that explanation is an inference.
What limits it. Shares in smaller counties rest on a few thousand applications. Two years of data.
Who still uses them
| Measure | 2022 | 2023 |
|---|---|---|
| Licences reporting any second-generation application | 748 | 660 |
| Share made by the largest licence | 9.1% | 13.6% |
| Share made by the largest 5 | 39.7% | 51.6% |
| Share made by the largest 10 | 61.9% | 66.2% |
| Share made by the largest 50 | 84.6% | 87.3% |
Source: California Pesticide Use Reports 2022 and 2023, site code 10, licence numbers standardised for spacing. We name no business. Author calculation.
What it means. The remaining use is far more concentrated than pest control work overall. Our licence census found the largest tenth of licences, more than 400, made four fifths of all structural applications; here, ten licences make two thirds of the restricted-rodenticide applications. The largest five operate across many counties; one reported second-generation use in 17 counties in 2023. Concentration rose between 2022 and 2023 as the number of licences using the compounds fell by 88.
What limits it. Licence numbers are entered inconsistently, so a single business could appear under more than one number; standardising only spacing, the counts above are, if anything, an understatement of concentration. A licence’s use may be entirely within the law’s exemptions.
Rodent baiting per home
| County | Rodenticide applications per housing unit, 2022 | 2023 |
|---|---|---|
| Humboldt | 0.42 | 0.64 |
| Napa | 0.38 | 0.39 |
| Santa Barbara | 0.37 | 0.34 |
| San Diego | 0.36 | 0.37 |
| Monterey | 0.33 | 0.31 |
| California | 0.21 | 0.21 |
| Los Angeles | 0.18 | 0.19 |
| Santa Clara | 0.14 | 0.13 |
| San Francisco | 0.12 | 0.13 |
Source: Pesticide Use Reports 2022 and 2023, site code 10, all rodenticide applications; US Census Bureau housing unit estimates. Counties with 50,000 or more housing units. Author calculation.
What it means. Structural rodent baiting runs at about one application for every five housing units statewide, and nearly twice that in several coastal and North Coast counties. It is low in the Bay Area, around one application for every seven to eight housing units, and lowest in a few inland counties such as Shasta and Imperial.
What limits it. Applications include commercial and food-industry sites, not only homes; a single food plant with many bait stations can raise a small county’s rate.
What comes next
AB 1322, signed in October 2023, extends a statewide prohibition with similar exemptions to diphacinone, the first-generation anticoagulant that replaced most second-generation use. Diphacinone was used in 1,203,949 structural applications in 2023. The 2024 use reports, not yet published, will show whether the same counties and the same small group of licences carry the exempt use of diphacinone too.
Checks
1. Totals reconcile
Result. County totals sum to the statewide figures in our rodenticide ban report: 3,017,398 rodenticide applications in 2022 and 3,042,550 in 2023; 319,647 and 263,926 second-generation applications.
2. Two years
Result. Central Valley counties lead the second-generation share in both years; in 2022 the shares were higher still, at 56.5 percent in Merced, 51.0 in Tulare, 47.4 in Stanislaus and 44.0 in Fresno. Concentration among licences is above 60 percent for the top ten in both years.
Related research: rodenticide use by sector.
Download the data
The tables in this report are published as CSV files under a Creative Commons Attribution 4.0 licence. You may republish, remix and build on them, including commercially, with attribution to The Pest Control Brief and a link to this page.
- Rodenticide and second-generation anticoagulant applications by county, with rates per housing unit, 2022 and 2023 (CSV, 58 rows)
How to cite this report
The Pest Control Brief, “After California's Rodenticide Ban: Ten Licences Make Two Thirds of the Remaining Use, and the Central Valley Relies on It Most”, 2 October 2026. https://thepestcontrolbrief.com/california-rodenticide-use-by-county/
References
- California Department of Pesticide Regulation. Pesticide Use Report annual archives for 2022 and 2023. files.cdpr.ca.gov/pub/outgoing/pur_archives/. Accessed 3 October 2026.
- California Legislature. AB 1788, California Ecosystems Protection Act of 2020. leginfo.legislature.ca.gov AB 1788. Accessed 2 October 2026.
- California Legislature. AB 1322, California Ecosystems Protection Act of 2023. leginfo.legislature.ca.gov AB 1322. Accessed 2 October 2026.
- US Census Bureau. Annual Estimates of Housing Units for Counties in California (CO-EST2023-HU-06). www2.census.gov. Accessed 2 October 2026.
How the figures were built
Scope. Every 2022 and 2023 Pesticide Use Report record with site code 10 naming one of eleven rodenticide active ingredients.
Measures. Application counts by county of use, compound and reporting licence. Second-generation compounds are the four AB 1788 names.
Licences. Standardised by removing spaces and upper-casing; no other merging.
Limitations. Structural pest control only. The reports do not record which legal exemption applied. California only.
Last reviewed: 3 October 2026.
For reporters covering rodenticides
Most quotable statistics
- Ten pest control licences made 66.2 percent of California’s structural second-generation rodenticide applications in 2023, two years after the state’s restriction.
- 660 licences still reported some second-generation use in 2023.
- In Merced County the restricted compounds were 48.6 percent of structural rodenticide applications in 2023; in San Diego County, 1.8 percent.
- Los Angeles County had the most second-generation applications, 54,514, a fifth of the state’s.
Caveats that travel with them
The remaining use may be entirely within the law’s exemptions; the reports do not say which applied. No business is named.
Press summary
The second-generation rodenticides California restricted in 2021 are still used by hundreds of pest control licences, but two thirds of that use comes from just ten, according to an analysis of state pesticide use reports by The Pest Control Brief. The restricted compounds remain a third to a half of structural rodent baiting in several San Joaquin Valley counties, against under a tenth along the southern coast. The state’s law exempts food warehouses, processing plants and similar sites, though the reports do not record which exemption applied.
Headlines editors could use
- Ten licences do two thirds of California’s remaining banned-rodenticide use
- In the Central Valley, restricted rodenticides are still half of rodent baiting
- Where California’s rodenticide ban has the most exceptions
Questions readers ask
Are second-generation rodenticides still used in California?
Yes, under exemptions. Structural pest control reported 263,926 applications in 2023, down from 2.13 million in 2020.
Who still uses banned rodenticides in California?
660 pest control licences reported some use in 2023, but ten made two thirds of it. We do not name businesses.
Which counties use the most?
Los Angeles in number of applications; Merced, Tulare and Stanislaus as a share of rodent baiting, at 40 to 49 percent.
Why is use higher in the Central Valley?
The data do not say. The law’s exemptions for food warehouses, processing and similar facilities are a plausible reason.
Is it legal?
Use is allowed under the exemptions in AB 1788. The reports do not record which exemption each application relied on, so legality cannot be assessed from them.
Where can I get my county’s figures?
All 58 counties are in the CSV above.
