Want to catch them without chemicals? Use a damp newspaper or a slice of potato. Seriously, it works. Roll up a newspaper, wet it, and place it in a shady spot. Check it the next morning—you’ll find a woodlice convention under there.
How to Get Rid of Woodlice in the Garden - Garden Doctor
Scoop them up (gloves optional) and relocate them to a compost heap far from your prized petunias. This isn't cruel; it’s just a very gentle eviction notice. Repeat this for a week, and their population will drop like a bad habit.