There are several management/control options
for slugs. First and foremost is to remove their habitat. Avoid debris
left in the garden that provides a hiding place. Encourage air movement.
Using less mulch may not seem practical but will reduce the slug population.
Some plants may be mulched that don't need mulching; a mature hosta plant
will shade the ground and limit any weed competition.
Some plants may appear less desirable to slugs. While many hostas seem
to attract slugs like a magnet, many of the blue types and/or those with
"waffled" leaves seem unaffected. Succulents, ivy, and ripening produce
are also attractive food sources.
Certain mulch material tends to be less attractive to slugs. Cedar chips,
pine needles and rinsed, crushed egg shells tend to repel slugs, either
due to odor, resin and/or sharp edges. In fact, many hosta growers are
reporting remarkable successes with pine needles applied two to three inches
thick. Needles will not significantly disturb the soil pH.
Hand picking slugs and crushing them (or placing them in a jar or bag
for disposal if you're squeamish) is another alternative, especially during
the evening and early morning hours. Slugs can be trapped under boards
or overturned flower pots and removed. Keep the traps in the garden several
days before removing to allow slug populations to discover a new "hiding
place."
SLUGS--BAITS
Beer baits aren't as effective as many are led to believe. If used, bury
saucers of containers of beer at ground level. Several saucers or containers
may need to be buried in an area, emptied daily and refilled. Cans with
plastic lids can be used with holes cut into the side and buried to the
hole; this prevents animals from discovering the beer and draining the
bait. Slugs are attracted to the yeast smell and drown. However, slug populations
may be too large for this method to be effective. However, some degree
of control is better than none.
Slug baits (poisons) are available at many garden center, nurseries
and discount stores. Most of the products contain metaldehyde or Mesurol.
Baits can be pelletized or powdered. Pelletized baits tend to provide longer
residual than powdered forms. Most baits need to be moist in order to attract
slugs. Replenish baits when dissolved or removed. Baits may be attractive
to some pets; use cautiously. Make sure to read and follow all instructions.
SLUGS--BARRIERS
Hardwood, softwood and diatomaceous earth barriers against slugs can be
used if kept dry. Diatomaceous earth may be lung health hazard if breathed;
face masks should be used when applying.
Copper barrier strips create an impenetrable barrier to slugs. Copper
flashing or sheets available at hardware stores can be cut and attached
to wood frames. Slugs will not crawl over the copper barrier used as strips
around individual plants. Any slug already in the area when barriers are
put down will not be killed or affected. It might be wise to check an area
before creating a barrier. Slugs will not cross copper due reaction between
the copper and their bodies.
Ducks, chickens, toads and rove beetles will eat slugs, though neighbors
may complain about the noise from the first two. Other birds may eat slugs,
though they are seldom active during the same hours of the day.
The use of salt to "melt" a slug isn't recommended. While it may kill
the slug, the salt will cause problems with the soil and surrounding plants.
SLUGS--BIOLOGY
Slugs have been described as snails without shells, though slugs have a
"shell" hidden by the fleshy mantel on their back. They are neither an
insect nor relative of the spiders. Like insects and spiders, they're also
classified as Arthropods, but belong to the mollusc family.
Slugs travel on a slime trail excreted by their single large foot. Eyes
are located at the end of the large tentacles on their head. The small
tentacles contain organs of smell. Slugs are hermaphroditic -- both sex
organs are located on the creature. Cross-fertilization is more common,
but under extreme situations, slugs can fertilize themselves, which is
an interesting survival technique. Eggs may lay dormant until sufficient
moisture is available for hatching.
Slugs prefer a moist, humid environment. They tend to avoid the sun
and feed at night. Birds find slugs a satisfactory food, which is another
reason for night feeding. Most slugs will hide in soil crevices, earthworm
holes, or under leaves, boards or other garden debris during the day. Most
slugs will return to the same "nesting" site each evening unless it dries
out.
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