How do I get rid of Vallonia costata (grass snails) in my lawn
Carteret County North Carolina
I had to look this one up. I can't find any specific control measures for this particular snail. I can't even find a list of what it eats. I am going to guess that this is more or less just being a nuisance to you in that you are seeing a lot of them. If this is the case and they are concentrated in a specific area, here are a couple of things you might do to get rid of some or most of them.
1. Snails and slugs tend to hide under things during the day. If you take a board (2 by 4 or wider) and place it in the area where you are seeing the majority of the snails and leave it over night, the next day you can pick up the board and the bottom should be covered with the snails. You can then smash them on a hard surface, scrape them into a bucket of water or dispose of them in some other manner of your choosing. A few days of this and you should have a majority of them out of the area.
2. There are slug and snail baits on the market that can be used to kill these pests. If you go this route, make sure you read and follow the label directions for using the product you choose.
3. I read several accounts of using beer as a bait to drown the snails. You are welcome to try this method. I have never had success with this, but there are others who say it works wonders. I wonder if they aren't sampling the bait before making the application.
The little bit of information I did find on this mollusk is that it is generally not found this far south. If you have a sample you could drop by the Extension office in Morehead City (303 College Circle the office is on the 3rd floor) I can see if I can get it identified and make sure it is the snail you think it is. This would help map the range of this species so others can be on the look out for it.
I hope this information is helpful.