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Pest Profiles: Invertebrates

Invertebrate pests – insects, spiders and mites, snails, and slugs

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Snails can mow down new transplants in one night. Photo: Pexels
Snails can mow down new transplants in one night. Photo: Pexels


An invertebrate is any animal without an internal backbone including insects, spiders, mollusks, crustaceans, and worms. 

Insects (Arthropods) 

• Have three main body segments, three pairs of walking legs, and antennae 
• Live in the air, on and in soil, and in water
• Majority are harmless or even beneficial; less than 1% are considered pests 
• Aid in the production of fruits, seeds, and vegetables by pollinating blossoms
• Improve soil’s physical condition by burrowing throughout the surface layer 
• Some parasitize or prey on harmful insects
• Serve as food sources for birds, fish, mammals, reptiles, and other animals

Spiders and mites (Arachnids)

• Have two main body segments, four pairs of walking legs, and no antennae
Spiders are generally beneficial because of the large number of insects they eat 

Snails and slugs (Mollusks)

• Move by gliding along on a muscular “foot” 
• The “foot” constantly secretes mucus that helps them move and later dries to form the silvery slime trail

> GARDEN PESTS:
> Vertebrates
> Diseases

 

Get detailed information on common invertebrates in Marin gardens, how to identify and manage them in your household and garden:
 
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Ant
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Ants

Prevalent household pest in households. Most common outdoor ants in California are Argentine ants. Body is constricted, giving appearance of a thin waist, which distinguishes it from termites. Adults, known as workers, are wingless. Pharaoh ants are found indoors. Carpenter ants damage wood structures…
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Aphids
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Aphids

 Small insects that suck fluids out of stems, leaves, and other tender plant parts. Soft pear-shaped bodies with long legs and antennae and may be green, yellow, brown, red, or black. A few species appear waxy or woolly due to the secretion of a waxy white or gray substance over their body surface…
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Cucumber beetle
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Cucumber Beetles

Common vegetable garden pest that also attacks ripening stone fruit. Adult beetles are shiny with black heads, long antennae, and about one-quarter inch long. Striped or spotted depending on species. Larvae are whitish and slender with three pairs of short legs; the head and tip of the abdomen are darker…
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cutworm
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Cutworms

 Cutworms are dull brown caterpillars one to two inches long when fully grown. They curl into a C-shape when disturbed. Some clip off seedling stems, while others chew or bore holes. CategoryInsectSigns/SymptomsCutworms feed on blossoms and leaves of many ornamental plants and attack most edible…
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Earwig
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Earwigs

 Earwigs can devastate seedling vegetables or annual flowers and often seriously damage maturing soft fruit or corn silks.  They also have a beneficial role in the landscape and have been shown to be important predators of aphids. Although several species occur, the most common in California…
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Grub
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Grubs

 Masked chafers are also called white grubs. They are beetle larvae, white with brown head, up to one inch long with bristles on underside. Produce one generation each year and overwinter as mature larvae. In spring and early summer, they pupate three to six inches deep in the soil.CategoryInsectSigns…
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Leafminer
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Leafminer

Leafminer larvae attack many vegetables and ornamentals. Male and female flies pierce leaves and suck sap. Female lays eggs between the leaf layers. When the larva hatches, it uses its mouth parts to rupture plant cells, weaving trails through the leaf. These trails are called mines.CategoryInsectSigns…
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Scale insects
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Scale

Adult scales are immobile with coverings that are one twenty-fifth to one-quarter inch long. Immature scales are small slow-moving bodies called crawlers that have legs which eventually drop off. There are two main groups of scale insects — soft and armored. Soft scales have a more rounded and convex…
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snails and slugs
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Snails & Slugs

Both snails and slugs are members of the mollusk phylum and are similar in structure and biology, except that slugs lack the snail's external spiral shell. These mollusks move by gliding along on a muscular “foot.” This muscle constantly secretes mucus, which facilitates their movement and later dries to…
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Thrips
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Thrips

 Thrips are tiny, slender insects with hairs on their wing margins. They are less than one-twentieth inch long and their color varies depending on the species and life stage.Thrips hatch from eggs and develop through two feeding and two non-feeding stages before developing into adults.Most pest…
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