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Pest Profiles: Invertebrates

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

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:
 
hornworm
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Tomato Hornworm

Often the largest caterpillars seen in vegetable gardens – up to four inches long. Horn or thorn at rear end. Adult moths have wingspan up to five inches.CategoryInsectSigns/SymptomsHornworms feed on blossoms, leaves, and fruit. At high populations they can extensively defoliate plants and scar the fruit…
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whitefly
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Whitefly

Piercing, needle-like mouth parts suck sap from food-conducting tissues in plant stems and leaves. Like aphids, whiteflies excrete sugary liquid called honeydew, so leaves may be sticky or covered with black sooty mold. The honeydew attracts ants, which interferes with the activities of natural enemies that…
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yellowjacket
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Yellowjackets

Yellowjackets are one-half to one inch long with jagged bright yellow and black stripes. Their narrow “waists” are barely visible. Unlike other common wasps, yellowjackets scavenge on food. They nest in holes in the ground, inside wall cavities, or in hanging nests totally enclosed in gray paper with a…
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Ant
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Ants

In the Bay Area, the most frequently found ants populating our gardens and invading our homes are Argentine ants. Argentine ants are small (1/8”), and their queens are slightly larger. Their bodies are constricted, giving them an appearance of a thin waist, which distinguishes them from termites. …
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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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