What the California rodenticide rules changed
If you have looked for rat poison recently and found the shelf thinner than you remembered, that is policy rather than supply. California prohibits most uses of both first and second generation anticoagulants: bromadiolone, brodifacoum, difethialone, diphacinone, chlorophacinone and warfarin. Bromethalin, cholecalciferol and zinc phosphide remain, with their own limits. The reasoning is secondary poisoning. An animal that takes an anticoagulant does not die immediately, and during that window it is slow and easy to catch, so hawks, owls, bobcats and household pets end up eating the dose. The restrictions were written to break that chain. For a homeowner in Fresno, the practical effect is a change in what a plan looks like. Bait was never the part that solved anything permanently, but it did mask problems, and a monthly station service could keep numbers down while the building stayed exactly as it was. That option has narrowed. What replaces it is not exotic. It is snap trapping on a real schedule, with someone returning to check and reset, plus closing the openings so the population outside cannot resupply the population inside. If a provider's proposal still reads like a bait program with sealing mentioned in passing, ask them to explain what they are applying and under what conditions it is permitted.
The two measurements that matter
Exclusion work runs on two numbers, and knowing both lets you check somebody else's work. The first is a quarter of an inch. Any hole larger than that should be closed, because that is the threshold for a mouse and the starting point for a rat, which will gnaw a small opening until it fits. That is the figure University of California guidance uses and the CDC repeats with a pencil for scale. The second is half an inch, which is the gap a rat can squeeze under a door. Door clearances are the most commonly overlooked opening on a property, partly because they look intentional. A worn threshold, a garage service door that no longer sits flat, a shed door with a warped bottom rail: all of these read as normal wear rather than as an entry point. Carry those two numbers when you walk your own building. Anything you can slide a pencil into gets closed, and any door you can see daylight under gets a sweep. Materials matter as much as measurements. Hardware cloth, sheet metal, mortar and metal sweeps hold. Expanding foam, caulk and plastic mesh are chewed out, often within a few nights, and their failure is what convinces people that sealing does not work.
Living next to farmland and irrigation
A Fresno property does not sit in isolation. In a valley built around agriculture, there is almost always ground nearby that supports a rodent population regardless of what happens on your lot, and that changes what you should expect from a plan. Start with the outdoor picture. Roof rats travel over 300 feet between nest and food, so the animals working your yard may be living well beyond your fence. That is not a reason to give up on the exterior, but it is a reason to stop expecting the outdoor half of the job to ever be finished. Clearing cover, keeping feed in hard containers and picking fruit promptly reduce what your property offers, and that is the realistic goal. Water is the second half. With 11 inches of rain a year, irrigation is what makes a place habitable, and the animals know it. Drip tubing, valve boxes, hose bibs and condensate lines are fixed points on their nightly route, and chewed tubing is often the first evidence people notice. The conclusion is straightforward. Because you cannot control the surrounding ground, the building envelope is where your money does the most work. Seal it properly and the pressure outside becomes somebody else's problem rather than yours.
Sheds, stored equipment and deer mice
The riskiest space on a Fresno property is usually not the house. It is the shed or the piece of equipment that has been sitting since last season. Deer mice are an outbuilding animal. They nest in stored gear, under seats, in air filter housings, inside sacks and behind boxes, and they leave droppings that dry thoroughly in a climate at 54 percent humidity. California recorded four provisional hantavirus cases in 2025, the highest state count that year, and the exposure route in every case of this kind is the same: someone breathes air in an enclosed space where dried droppings have been disturbed. So the order of operations matters more than the tools. Open the building and walk away for thirty minutes before anyone goes in. Come back with gloves and a sprayer of bleach solution mixed at roughly a cup and a half per gallon. Wet everything, including material you plan to discard, and give it five minutes. Wipe up with paper towels, bag the waste, then wash thoroughly. Only after that is it worth thinking about sealing the building and setting traps. Doing it the other way around means the first sweep of a broom has already done the damage.
How to compare two proposals
With bait options narrowed, the differences between rodent proposals in California are mostly about labor, and labor is what you are actually buying. Ask how many trap service visits are included and who performs them. Under the current rules, trapping is doing the removal work, and a plan with a single visit and no return dates has quietly left out the part that matters. Ask whether openings are listed individually with a material named for each. A single line that says exclusion cannot be verified after the crew leaves, and it usually covers less than you imagine. Ask which structures are included. On a lot with a house, a garage and a shed, this question moves the price more than almost anything else, and it is regularly left implied. Ask what is being applied, if anything, and under what conditions it is permitted. A provider who can answer that clearly is one who has kept up with the rules. Finally, ask what happens if activity resumes in six weeks. The honest answer involves another inspection to find the missed opening, not simply more traps in the same places.