cherry slugs for the first time

I noticed cherry slugs on my cherry and pear tree for the first time last week. As i don't use any chemicals (or even homemade organic mixtures much) i decided to try something else - i sprinkled wood ash over my small trees.  I keep some wood ash in a bucket in my garden shed which i put a cup full into a small empty pot and then used it like a sifter to shake the ash over my trees.

The cherry slugs sit on top of the leaves, unlike other bugs and caterpillars that hang underneath.  It worked, the next morning the slugs had died and most of the ash had blown off. I shook the rest off and today it rained so i know the little that remained won't burn the leaves