Hello at the market garden I worked at we had a big toad that patrolled a green house 120feet ×110 feet there were never any slugs ,it use to be in a wet hole in a corner which the dog knew about and would nose the toad out and make it jump up the length of the greenhouse turn it round and make it jump back to the wet hole,we use to make sure the toad was in the wet hole before cutting lettuce,if it wasn't there we looked for it or worked very cautiously till we found it,if we found slugs it had missed they were put on a plate for it near the wet hole jezza