I have a big snail population in my yard. I don’t use pesticides and I want to avoid Sluggo or other iron phosphate type baits.
I have read online that decollate snails (Rumina decollata) eat brown garden snails (Helix aspersa). I’m thinking about ordering some of these as they say the decollate snails don’t eat your plants. Also I’ve read that garter snakes will eat the slugs and snails.
Decollate snails may not be imported into the Pacific Northwest. See this information from Oregon State University on nursery pests, excerpted here:
“Decollate snails, Rumina decollata, have been reared and released as biological control agents to control brown garden and other snails. They are native to the Mediterranean and have been in the US since the 1820s and in southern California since the 1950s. They are commercially available and have been used rather commonly in citrus orchards in California. They can harm native snails and are also plant feeders themselves. Decollate snails are prohibited from shipment to the Pacific Northwest but have managed to slip in at times.”
Oregon also lists Rumina decollata on its 2003 Invasive Species Report Card, and states that it is polyphagous, eating both plants and other snails:
“decollate snail, Rumina decollata (a polyphagous species that consumes both plant material and other snails, promoted as a biological control agent in areas heavily infested with European brown garden snail in California, reported for sale in a Eugene garden center in 2003)”
The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) also states that decollate snails cannot be permitted across state lines:
“Decollate snails (Rumina decollata) and aquatic snails in the family Ampullaridae (e.g., Pomacea canaliculata, channeled apple snail), with one exception, may not be imported or moved interstate except for research purposes into an APHIS inspected containment facility.”
I’m not sure I’d recommend importing garter snakes, though there may be natives already in your garden or surrounding areas. See the Washington Department of Fish and Wildlife’s information about our native species, which includes tips for attracting snakes.
There are much easier methods than the above for controlling destructive snails. The same traps that work for slugs–beer in saucers, upturned melon rinds, or copper barriers around plants–should help. A vigilant eye will catch lots of them, too, and they can be squished if you aren’t squeamish. More information from University of California, Davis Integrated Pest Management is here.
I understand your reluctance to use iron phosphate products like Sluggo. Although it is certified as acceptable for organic use by the Organic Materials Review Institute (OMRI), information published on the website of Oregon State University in May 2013 quotes recent research suggesting that even “less toxic” iron phosphate slug bait can cause iron toxicosis, and should be kept away from animals and children. Here is a fact sheet from the National Pesticide Information Center which explains the risks. Stormwater runoff may also be a concern, although one typically doesn’t use much of the stuff at a time. You might borrow a duck or two to come in and do some serious snail-eating!