Not all snails are not plant pests snails, however ... snails are Gastropods and there are over 40,000 species. There are carnivores and herbivores (vegetarians.)
Some herbivores, such as the Florida tree snails are beneficial in gardens (they eat algae, not leaves and bark.)
They are safe for your bonsai trees and may even clean your pots. Look for herbivores in your area. Others are bad, really bad.
“In 1966, a Miami, FL, boy smuggled three giant African snails into south Florida upon returning from a trip to Hawaii. His grandmother eventually released the snails into her garden.
Seven years later, more than 18,000 snails had been found along with scores of eggs. The Florida State eradication program for these plant pests snails took 10 years at a cost of $1 million.”
Now it's back!
If you see a snail that looks like this one, even if it's in a pet store, please report it to your State Department of Agriculture!
Or US Department of Plant Industry at 1-888-397-1517
Snails have something in their mouth called a radula (much like a rough tongue.)
The radula of the giant African snails allows them to devour such things as limestone, stucco, cardboard, paper and bark, in addition to leaves and stems. And, can pose a serous health risk to humans.
This is what a snail radula looks like in action:
The Cuban Brown snail is another voracious plant eater. It is prolific in South Florida. The eggs often travel when plants are shipped.
Their rasping mouth parts are strong enough to strip the bark and cambium layer off many plants. They are definitely plant pests . . . nothing beneficial about them.
'The Integrated Pest Management Program at University of California, Davis may have the answers, you're looking for!
"The first step is to eliminate, as much as possible, all places where they can hide during the day. Boards, stones, debris, weedy areas around tree trunks, leafy branches growing close to the ground, and dense ground covers such as ivy are ideal sheltering spots."
There are many more suggestions on the site.
My favorite suggestion is traps: "You can trap snails and slugs beneath boards or flower pots that you position throughout the garden and landscape. Inverted melon rinds also make good traps. Construct wooden traps using 12- by 15-inch boards (or any easy-to-handle size) raised off the ground by 1-inch runners.
"The runners make it easy for the pests to crawl underneath. Scrape off the accumulated plant pests snails and slugs daily and destroy them; crushing is the most common method. Don’t use salt to destroy snails and slugs, since it will increase soil salinity."
Do Not use snail bait. Yes, it works, but it doesn't know the difference between the helpful snails and the evil doers. In addition, it can be very dangerous to pets.
Even if you don't live in Florida, it's possible for these snails to show up in plants received from that area. Although plants from reputable growers are usually pest free, sometimes it's difficult to see snail eggs.
Florida and California are not the only places with snail problems. Be sure you know the snails where you live.