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Exploring the beautiful nature of California
California Nature: Garden Pests
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Problems with plants can be caused either by
vertebrates, such as rodents or deer, invertebrates like
nematodes, insects or mites, or fungi and disease. The first
step in pest management is selecting the right plant for the
right area. Choosing the right plant for your site will
translate into healthier plants and reduced pest problems. Water
needs, soil type, exposure, and function and form all enter into
the selection of an appropriate plant or landscape suite.
Mollusks that damage plants are either snails or slugs, both of
which are found in almost every California garden.
Destructive chewing insects include aphids, scale, several types
of beetles and tomato hornworms.
You might need to protect your plants against a few kinds of
small mammals as well: opossums, raccoons and rats often live in
residential areas and can cause extensive damage to ripening
fruit and other plants.
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Aphids or "plant lice" are soft bodied pear-shaped insects generally less than 1/8 inch long. Their color varies according to species, however the common aphids are usually green, yellow or black. The most distinguishing feature in the identification of aphids is the two short cornicles or tubes which extend from the end of their body. These structures are partly responsible for secretions of a fluid thought to be useful as a defense mechanism.
Most aphids, even adults, are wingless but when colonies become overcrowded or the host plant becomes undesirable, winged forms are produced and these establish new colonies. In
California, almost all aphids are females which reproduce without mating! Each female aphid produces 50 to 100 daughters during her life span, and each daughter can begin reproducing in six to eight days. Aphids have piercing-sucking mouthparts and cause damage by sucking the plant juices. They are commonly found on the stems, undersides of leaves and on flower buds in colonies of individuals. However, their ability to transmit plant virus diseases may be more harmful than any direct feeding damage.
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Slugs and snails won’t do any damage to the house or other structures, but they
can do some serious damage to gardens. That damage can be just as devastating
for those who spend hours every week in the garden or depend on the garden for
fruits and veggies. Both slugs and snails belong to the mollusk family and are similar in structure
except snails have the outer shell. They move around with a muscular foot that
releases a slimy substance that is often described as silvery or iridescent. The
mollusks are most active at night and can also be seen during or after it rains.
Slugs and snails chew holes in leaves, fruit and veggies and will target both living and decaying plants. Their damage is often confused with the damage caused by caterpillars but can be easily confirmed once the mucus trail is identified.
Pouring salt on slugs and snails will kill them but the added
salt may not be beneficial for the garden. Toads love
snails and slugs and the amphibians are actually good for the
garden. Turtles, snakes and birds will also make a meal out of
snails and slugs.
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The tomato or tobacco hornworm starts life as
tiny larva, but very quickly it can grow to 4
inches long and as thick as your index finger as
it munches through your garden. One hornworm can
defoliate an entire tomato plant if it isn't
stopped in time. I had some hornworms attack my
tomato plants this summer and the amount they
ate in twenty four hours is incredible! Tomato
hornworms feed only on solanaceous plants, most
often on tomato. However, larvae will also
attack eggplant, pepper, and potato. There are
many solonaceous weeds that also serve as
alternate hosts, including: horsenettle,
jimsonweed and nightshade.
Eggs of the tomato hornworm are deposited singly
on both the lower and upper surface of leaves in
late spring. The eggs hatch in six to eight days
and are oval, smooth, light green to yellow in
color, and measure 0.10 cm in diameter. The
caterpillar reaches the final instar in 3-4
weeks, and is 3 1/2 to 4 inches when fully
mature. Fully-grown larvae then drop off of the
plants and burrow into the soil to pupate.
During the summer months, moths will emerge from
pupae in about 2 weeks. Moths emerge from the
soil, mate, and then begin to deposit the eggs
of the next generation on tomato plants. By
early fall, the pupae will remain in the soil
all winter and emerge as a moth the following
spring. |
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The armored and soft scales are one of the
most destructive groups of insects that attack ornamental crops.
The armored scales secrete a waxy covering over their bodies.
This covering is not an integral part of the insect's body. The
scale lives and feeds under this covering which resembles a
plate of armor, hence the name. They vary in size from 1/16 inch
to 1/8 inch in diameter and can be almost any color, depending
on the species. Armored scales may be circular, oval, oblong,
thread-like, or even pear-shaped. The female's armor is larger
than that of the male, while the shape and color may be similar
or distinctly different, depending upon the particular species.
The eggs are laid underneath the waxy covering and hatch over a
period of one to three weeks. The newly hatched scales (called
crawlers) move about over the plant until they locate succulent
new growth. They insert their piercing-sucking mouthparts into
the plant and begin feeding. Scales cause damage by sucking the
juices from the plants. Heavily infested plants appear unhealthy
and produce little new growth. Scales feeding on the undersides
of leaves may cause yellow spots to appear on the top sides, and
these spots progressively become larger as the scales continue
to feed. If the scales are not controlled, leaves will drop
prematurely, sometimes killing portions of twigs and branches.
Scales also feed on trunks and stems of plants.
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Butterflies
Creepy Crawly Pests Flying Pests
Garden Pests
Itchy, Stingy Bugs |
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