Slugs work at night
This photo shows a four-inch-long banana slug slithering into a hole in a forest near Burnt Woods, Oregon.
Chewed leaves are likely the handiwork of slugs, nocturnal creatures that especially love wet weather. These slimy creatures, from a couple of inches to half a foot or more in length, are basically snails without shells. Besides leaving ragged leaves, slugs make their nocturnal presence known the morning after by the shiny trails they leave behind.
Slugs avoid anything sharp or caustic against their slimy bodies, so if you sprinkle a circle of sharp sand, diatomaceous earth (the kind sold at garden suppliers, not the kind used for swimming pool filters) or wood ashes around your plants, a slug will think twice before crossing this barrier. Renew these barriers after rains, when slugs are most active.
You could take a flashlight into the garden at night and sneak up on slugs while they are at work. Mano a mano combat is difficult against these slimy creatures, though, so take along a saltshaker. Sprinkling salt on them will kill them.
Beer is also an effective poison bait for slugs. Put a shallow pan of beer on the ground, and almost immediately slugs will start inching to their demise. No need to open a fresh bottle each night; slugs are happy even with stale beer. Some gardeners report good results with only yeast plus water. Be aware that it is possible to attract more slugs to an area with a beer or yeasty attractant.
