Q: I heard that California has restricted the use of some rodent poisons and that some baits that were once legal are now restricted. Can you give us an update on what is now restricted and what is okay to use?
This is a subject especially close to my heart (and wallet) since we just spent over $700 to repair rat damage to my husband’s car.
California’s Poison Free Wildlife Act, which took effect earlier this year, expands the list of restricted poisons in California. Some of the poisons that are no longer legal include brodifacoum, bromadiolone, chlorofacinone, difethialone, diphacinone, strychnine, and warfarin. Most of these poisons are anticoagulants, with the exception of strychnine, which is a potent neurotoxin. Previous legislation targeted the so-called “second-generation” rodenticides, which were thought to be especially harmful to non-target wildlife. Now the list of restricted poisons has been expanded to include the older rodenticides since they have been affecting non-target wildlife as well. This means that the list of “safe” rodenticides that I included in a previous column is no longer valid.
Currently, the list of approved rodenticides for household use in California includes bromethaline, cholecalciferol, and zinc phosphide. For more information, go to Home & Garden Pest Newsletter volume 2 issue 2 on the UC IPM website.
Q: I’ve read about birth control baits for rats and mice. Are these safe and effective? How do they work?
I found very little information online about the various birth control baits available. The active ingredient is cottonseed oil, which is relatively harmless. I’ve ordered some, but I’m not equipped to perform a valid scientific study to determine its effectiveness. In other words, I’m not going to count rats. The manufacturer does state that it is part of a comprehensive rodent control program, so I wouldn’t expect it to work if you leave your pet food unsecured and nesting areas available.
I have been using an electronic repellent for my car and have noticed that the rats haven’t been leaving empty snail shells on the engine. As an added bonus, my husband no longer makes fun of me for being “paranoid” about rats.
I’ve also found a non-toxic rat and mouse bait that uses corn gluten meal and sodium chloride. Theoretically, the rodent eats the bait and dies from high blood pressure (well, actually, kidney failure due to hypernatremia). This makes me wonder if I could get the same results from leaving a bag of Doritos out. We’ll see…
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; 951-955-0170; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu