Laura Jesse, of Iowa State University Extension’s Plant & Insect Diagnostic Clinic, wrote the following about garden slugs:
Slug photo by Laura Jesse of ISU Extension
There seem to be plenty of slugs in my garden, but I hope not in yours. Slugs leave small, irregular holes all over the leaves of plants. They especially seem to like my hostas but they are not picky feeders. Slugs are difficult to detect because they feed only at night. Slugs look like snails without a shell. They vary in size from less than an inch up to 2 inches in length, grayish colored, and a bit slimy to the touch. In fact as they crawl along they leave a slime trail.
Slugs need moisture to survive and are found under mulch, rocks, logs, and other damp locations. My hostas tend to be eaten because they grow in a garden that is shaded and holds the moisture longer.
Reducing slug damage is not an easy task and nothing will fix holes already there, so your first question should be – how bad is this and can I live with the damage? If you do decide to try to reduce the slug population you should combine several tactics. First, remove mulch and reduce moisture from around the base of afflicted plants as much as possible. Remove slugs you find either by using a trap such as a board on the ground that slugs will gather under or pan traps with beer as a bait. I assume cheap beer works fine and would not waste expensive beer on this. Remove dead slugs daily or it will get pretty disgusting. Finally there are commercially available slug baits available containing a molluscicide, but they are best used in the spring or fall.
Linn County Master Gardener, Claire Smith, wrote the following: The driver of the car at the stop light next to me looked rather aghast when I broke into a hearty laugh this morning. I guess some radio and TV facts are just meant to be light hearted even though reported in a most serious manner, for example, the obnoxious little black flies that are so prevalent this spring are called buffalo gnats. Do you know why? Because they have a hump in their back. With no disrespect intended to those folks who study insects, that “need-to-know” fact really struck my funny bone.
Not so funny is in the onslaught of beetles again this year. Just a reminder, do not spray edible plants to rid the beetles. Traps seem fairly effective. The traps do attract the little critters in addition to killing them so it is suggested you locate traps at the ends of your property.
The ugly tunnels in your lawn are probably mole trails. Another little known fact is that moles eat more than their own weight in worms daily. Worms are good for the soil. They constantly aerate the earth. Keep the worms; eradicate the moles. The most practical method of eviction is a scissor or harpoon type trap. Locate the active tunnel by tamping down all of the tunnels. Place the trap in the one the mole reopens.
And then there are the garden invaders, the ground hogs, rabbits and raccoons. Probably the best offense against them is a good fence. Hardware cloth or wire mesh should be at least 1½ to 2 ft. tall supported with wood or metal stakes. Bury the fence into the ground a bit or secure it down with landscape pins. Repellents are somewhat effective, but more costly as they need to be reapplied after each heavy rain. You could consider live traps, but the last time we tried live traps, an opossum was smarter than we were. We did capture two cats, though.
And, finally, Oh! Deer! It is best to discourage deer before they become accustomed to the delicacies in your garden or yard. The most reliable deer prevention maintenance is a fence. However, a deer proof fence will be at least eight feet tall which can be a costly venture, be aesthetically unattractive, and possible prohibited by local building codes. Repellents and scare tactics are ineffective as deer ignore them. Try temporary fences around new plants and special plants. Deer may force you to choose plants that are less tasty to them, have an unusual texture, or a strong aroma. Call your local extension office (in Linn County 447-0647) for a list of deer resistant plants. Perhaps impractical in some cases, a good dog will be as efficient as anything else you might try.