Well,I also have back up or complimentary methods. One that I am using now is coffee grounds tightly around the base of individual plants ,especially cabbages etc since the slugs are very partial to them and after a night's vandalism like little better than to sleep it off at the base of the trunk during the day.

They do particular damage to the new shoots that appear at the bottom of the plant so I hope that by making this an unattractive area for them they will not develop a habit for feeding on my broccoli and kale.

Other methods have been home brewed nematodes (instead of the bought in kind) where I collect a very large quantity of slugs in captivity and wait until they die . Then I collect the funereal juices and spay this around areas of the garden in an attempt to spread the contagion to the previously healthy slug population.

But ferric phosphate pellets are the new white hope in my armory and that is why I am asking for help, in preventing the birds (or possibly mice) from getting to them before the slugs do.