Diatomaceous Earth is really the shells of microscopic algae called diatoms.
1) The fish would not crawl over it, so it would be safe. Diatoms are found in oceans all over the world.
2) It kills them by puncturing their protective outer layer and causes them to dehydrate...usually within 48 hours. So, it's not a satisfyingly dramatic death. Not like squirting the beasties with an ammonia/water solution or dropping them into boiling water, both of which require late-night slug-hunting patrols. (Can you tell which methods I prefer??)
3) If worms crawled over the Diatomaceous Earth, they would suffer the same fate as the slugs. Diatomaceous Earth is used to kill other bugs too. Ants come to mind. I must remember to sprinkle the ant hill in the flower bed once this rain stops (if it ever does...has it been 40 days, yet?)
4) It should be available anywhere garden supplies are sold. It might be sold under the name Diatomite.

I too like the late night slug hunting with Ammonia/water 1/10. Instant results! Joelle

Thanks Tiffy!

OK, so the squirrel found the slug bait dishes with the yeast mix and is eating it all. Somewhere in the woods behind our home, there is a squirrel with one heck of a belly ache!!!!!!!!

Hi,

I really like Safer's Slug and Snail Bait !! We moved to this house 2 years ago and the garden was totally infested with slugs and snails. I tried almost all the home remedies but with little success. I applied the bait (which can be used around pets, wildlife and birds) in the fall and again this spring. There are hardly any snails and slugs left. After a rainfall I find the odd one, thats it.
Hope this helps.
Erikka

I saved all my egg shells over the winter and sprinkled them crushed around the emerging hostas in the spring. It worked-not one bite. I then noticed my columbines being chewed so I used some more around them and no more damage. Like the diatomaceous earth, it pierces their bodies and they dehydrate, and the shells are relatively free. Here is the link I got the idea from which says DE lasts for decades but doesn't harm earthworms, although it may harm bees if they came in contact with a spray form.
Heather

Here is a link that might be useful: Gardenweb faq Natural Pesticidal and Fungicidal Recipes

I too use Safer's Slug and Snail Bait....haven't had a problem since. Tried the egg shell thing but my neighbours thought it was funny to see broken egg shells around my garden....Safer's is neater looking...for me anyway.

Heather, I'm relieved to find out that diatomaceous earth does not harm earthworms. It makes sense that DE would last in the soil for decades, since fossils don't decay quickly, but the directions tell us to renew the application following rain or watering. Hmmm. That wouldn't be just so we'll buy more DE, would it??

Safer's Slug and Snail Bait works for me, too. Don't know why I forgot to mention it in an earlier post. Probably because I don't see the gratifyingly instant results that I do with ammonia.

I used to go slug hunting, late at night, armed with a flashlight, long-handled tweezers and a bucket of boiling water. (I'm surprised the neighbours never called the police! I must have looked quite suspicious!!) I'd pluck the beasts off my plants and watch them disintegrate when I dropped each one into the bucket. I knew the water needed reheating whenever I saw slugs start to escape up the sides.

After a night of hunting, I disposed of the carcasses in the back alley, so the birds would have a feast the next day. Once, however, I guess the water had cooled off too much by the time I had caught the last batch for the night. I threw the slug water into the back alley and went to bed. The next day, my DH went to the alley for some reason, and he soon called me over. Not only had many slugs survived the "hot" bath, but all of them were crawling back towards my yard!!! Needless to say, they didn't make it. ;o)

Persistant little buggers they are!

I haven't tried the ammonia and water hunting at night, that sounds like a fun mission to get back at those pesky little slugs though!! I found some stuff at Lowe's called WORRY FREE by Lilly Miller Ferramol Slug & Snail Bait. Supposed to be safe around pets, children and wildlife.... wondering if anyone knew how effective it was or anything about it. Thanks for all the other great info though!!

I get great pleasure using a tiny bit of salt on the slugs. Only takes tinyest, lilke just a couple grains. I too go out late at night with my flashlight and always hope the neighbors don't see me. Only hostas lovers would understand and they don't have any hostas!

Just so you all know, DE does NOT lacerate or puncture slugs. The particles are WAY too small for that. All it does is desiccate them that's why it's completely ineffective as soon as it gets damp, let alone wet.

It's the same thing for exoskeletal insects. The abrasive quality is almost completely negligible. What it does to them is desiccate and strip away the protective, wax-like coating on their hard shell bodies, allowing their internal moisture to escape so they die of dehydration.

Food grade DE is completely benign and inert. It is no more harmful or irritating to inhale than any other type of dust. It's the calcined (heat-treated) DE made for pool filters that is the hazardous stuff. That's classified as a carcinogen through inhalation and can cause silicosis. Try to avoid breathing that stuff in.

I have a large collection of Hosta and the earwigs chew them to ribbons every year. This year I have been lifting the leaves and liberallydysting the stems and surrounding earth with diatomaceous earth. Not a hole in any of my beautiful leaves! Diatomaceous earth is my new best friend. I have been doing this on a weekly basis. I use the food grade.

This is the best stuff I have found

https://youtu.be/IcUp78KLHJ0