I haven't tried catching them this way but feeding them gets them in a small area. If you had a large net under the food you should be able to get most of them. I've fed them with lettuce but maybe not all species will like that.

That's a good idea tropicbreezent. I'll give that a try. I snuck up on a couple of them yesterday and caught them. I had also forgotten that instead of opening the bottom plug and letting it gush out too quickly, that I have an aquarium siphon thing that I used to let about 2/3 of the water out slowly. I let the rest settle and then try the rescue the rest of them before I open the big bottom plug. Even then, though, I run that through a net that would catch any. Funny how quickly they all disappear, even after I go to all the trouble of relocating them. Only 1-2 seem to develop into frogs next summer. But I can't bear to let them just die in the water as it flows out of the above ground tank. Now I do let the snails die. ......but I do apologize to them. ;)