Slug Control for All Seasons
Dealing with These Garden Pests is Not Strictly a Summer Task
Oct 6, 2009
Slugs and snails can be a gardener’s nightmare: In one evening, they can munch through a row of lettuce or shred a crop of cabbages and then return to their hideouts, leaving little more than a few slime trails to indicate who the marauders were.
According to Oregon State University entomologist Glenn Fisher, more than 90% of slugs are underground at any given time, so it isn’t possible to completely eliminate them. But it is possible to reduce their numbers so they don’t wreak total destruction on yards and gardens.
One basic tenet of slug and snail management is to understand that these creatures don’t just disappear when the cold weather sets in. Year-round control requires a bit of planning and persistence.
It is worth remembering that slugs do serve an underappreciated and ignoble purpose: They consume and recycle decomposing material in the environment. Unfortunately, they aren’t good at differentiating what can be eaten from what should be eaten.
When their indiscriminate dining brings them into the garden – as it most certainly will – slugs and snails must be dealt with as efficiently as possible.
Seasonal Chores That Help to Control Slugs and Snails
Every spring, mulch should be rolled over or pulled back from the bases of plants and shrubs. Overwintering slugs love to shelter under mulch or other heavy organic debris.
In summertime, slugs will take shelter beneath garden structures, within dangling leaves, under the rims of pots, or in any other location where they can hide from the sun. Frequent tipping or relocation of these items will reveal concealed slugs, and removal of excess foliage will eliminate their havens.
In the fall, compost piles should be broken apart and worked into the soil; leaf piles, branches, and other debris must be removed. Tilling helps to disrupt trails and exposes buried slugs and their eggs.
Chemical Baits for Slugs and Snails
Only two chemicals have been licensed in the United States for slug control:
- Metaldehyde (“Deadline,” “Slug-Tox,” “Cory’s Slug and Snail Death”) is supplied in liquid, granular, spray, or dust forms. Although classified as a “slightly toxic compound,” metaldehyde ingestion can be fatal to pets and wildlife.
- Iron phosphate (“Sluggo,” “Escar-Go!” and “Worry Free”), supplied in granular or pelleted form, is as effective as metaldehyde, but it is comparatively non-toxic to children, pets, and wildlife (ingestions of large amounts can lead to poisoning, however).
Slug and Snail Bait Basics
- Cereal-based baits (e.g., “Sluggo”) are more palatable to slugs than other forms.
- Baits should be applied after rain or overhead irrigation, when slugs are most active.
- In areas at high risk for wildlife, pet, or child exposure, placing baits beneath weighted “slug shelters” (plastic or terra cotta containers with notches cut in their rims) is recommended.
- Baits should be applied in spring to kill emerging slugs, and again in fall to address adults that are preparing to lay eggs. A late-fall application will kill many young slugs that have just hatched.
Natural Slug and Snail Control
- Hand-picking slugs and snails, while distasteful, is a relatively effective method for reducing their numbers. Early-morning forays with a container of soapy water and garden gloves are most productive. Follow the telltale trails of slime to find slugs. Look beneath overhanging leaves and beneath pots or other objects. Drop captured slugs into the container for later disposal.
- Place “slug skewers” – pointed sticks or wires – in several places around the garden. Whenever a slug is encountered during routine chores, use a skewer to impale and dispatch the beast.
- While effective, stepping on slugs or snails to squash them leaves one’s footwear besmeared with tenacious mucous. A mixture of vinegar, salt and warm water will slake the mess away (this also works well for inadvertently-slimed fingers).
- Beer-filled containers, buried to their rims around the garden, are a traditional means of attracting and drowning slugs. For those who cannot abide the thought of wasting even a stale beer on a slug, a mixture of one teaspoon each of sugar and yeast in a quart of water produces a viable alternative. Traps should be changed every couple of days.
- Surrounding precious plants with crushed eggshells, diatomaceous earth, pine needles, or copper strips may deter slugs and snails, but they will simply go elsewhere to feed.
- Pouring salt on slugs and snails may kill them, but this is an impractical method for dealing with heavy infestations; salt can damage plants and harm beneficial soil organisms.
- Garter snakes, chickens, ducks, and geese are natural slug and snail predators; not everyone can keep a flock of fowl, but everyone can leave the snakes alone to do their job.
Slugs and snails are a vexing part of gardening life; they will always be around. With just a little diligence, though, their role can be reduced to minor one.
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