Snails
and slugs are among the most bothersome pests
in many garden and landscape situations. The brown garden snail (Helix
aspersa), is the common snail causing problems in California gardens; it
was introduced from France during the 1850s for use as food. Several species
of slugs are frequently damaging, including the gray garden slug (Peroceras
reticulatum),the banded slug (Limax poirieri),and the greenhouse slug (Milax
gagates). Both snails and slugs are members of the mollusk phylum
and are similar in structure and biology, except slugs lack the snail's
external spiral shell.
IDENTIFICATION AND BIOLOGY
Snails and slugs move by
gliding along on a muscular "foot." This muscle constantly secretes mucus,
which later dries to form the silvery "slime trail" that signals the presence
of these pests.
Adult brown garden snails lay about 80 spherical, pearly white eggs at
a time into a hole in the topsoil. They may lay eggs up to six times a
year. It takes about 2 years for snails to mature. Slugs reach maturity
in about a year.
Snails and slugs are most
active at night and on cloudy or foggy days. On sunny days they seek hiding
places out of the heat and sun; often the only clues to their presence
are their silvery trails and plant damage. In mild-winter areas such as
in southern California and in coastal locations, young snails and slugs
are active throughout the year.
During cold weather, snails
and slugs hibernate in the topsoil. During hot, dry periods, snails seal
themselves off with a parchmentlike membrane and often attach themselves
to tree trunks, fences,
or walls.
DAMAGE
Snails and slugs feed on
a variety of living plants as well as on decaying plant matter. On plants
they chew irregular holes with smooth edges in leaves and can clip succulent
plant parts. They can also chew fruit and young plant bark. Because they
prefer succulent foliage, they are primarily pests of seedlings, herbaceous
plants, and ripening fruits [69K],such as strawberries, artichokes, and
tomatoes, that are close to the ground. However, they will also feed on
foliage and fruit of some trees; citrus are especially susceptible to damage.
MANAGEMENT
A good snail and slug management
program relies on a combination of methods. The first step is to eliminate,
to the extent possible, all places where snails or slugs can hide during
the day. Boards, stones, debris, weedy areas around tree trunks, leafy
branches growing close to the ground, and dense ground covers such as ivy
are ideal sheltering spots. There will be shelters that are not possible
to eliminate-- e.g., low ledges on fences,
the undersides of wooden decks, and water meter boxes. Make a regular practice
of removing snails and slugs in these areas. Also, locate vegetable gardens
or susceptible plants as far away as possible from these areas. Reducing
hiding places allows fewer snails and slugs to survive. The survivors congregate
in the remaining shelters, where they can more easily be located and controlled.
Also, switching from sprinkler irrigation to drip
irrigation
will reduce humidity and moist surfaces, making the habitat less favorable
for these pests.
Handpicking
Handpicking can be very
effective if done thoroughly on a regular basis. At first it should be
done daily; after the population has noticeably declined, a weekly handpicking
may be sufficient. To draw out snails, water the infested area in the late
afternoon. After dark, search them out using a flashlight, pick them up
(rubber gloves are handy when slugs are involved), place them in a plastic
bag, and dispose of them in the trash; or they can be put in a bucket with
soapy water and then disposed of in your compost pile. Alternatively, captured
snails and slugs can be crushed and left in the garden.
Traps
Snails and slugs can be
trapped under boards or flower pots positioned throughout the garden and
landscape. You can make traps from 12" x 15" boards (or any easy-to-handle
size)
raised off the ground by 1-inch runners. The runners make it easy for the
pests to crawl underneath. Scrape off the accumulated snails and slugs
daily and destroy them. Crushing is the most common method of destruction.
Do not use salt to destroy snails and slugs; it will increase soil salinity.
Beer-baited
traps have been used to trap and drown slugs and snails; however, they
attract slugs and snails within an area of only a few feet, and must be
refilled every few days to keep the level deep enough to drown the mollusks.
If using beer, it is more effective fresh than flat. Traps must have vertical
sides to keep the snails and slugs from crawling out. Snail and slug traps
can also be purchased at garden supply stores. Above article copyright
© 1995-2001 by the Regents of the University of California. All rights
reserved.
Pellets
Escar-Go!®
SupremeTM
- Proven snail, slug and insect killer!
Kills slugs, snails, earwigs,
cutworms, sowbugs, pill bugs, crickets and ants.The highly compressed pellets
are: easy to use, clean to handle, economical, effective for up to 4 weeks.
Where to use:
For use around vegetables,
fruit
trees, citrus, berries, ornamentals,
shrubs,
flowers, trees, lawns, gardens
and in greenhouses.
Application directions:
Scatter the bait granules
on the soil around or near the plants to be protected with a suitable hand-
or power-operated spreader (gravity or rotary) to ensure uniform coverage
over the treatment area. For slugs and snails, also scatter the bait around
the perimeter of the area to provide a protective “barrier” for those entering
the area. Evening is the best time to apply the bait, as pests travel and
feed mostly by night or early morning. If the ground is dry, wet it before
applying bait. The product works best when soil is moist but with little
or no standing water. |