UC Master Gardeners Logo
UC Marin Master Gardeners

Pest Profiles: Invertebrates

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

Image
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:
 
Primary Image
hornworm
Documents

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…
View Documents
Primary Image
whitefly
Documents

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…
View Documents
Primary Image
yellowjacket
Documents

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…
View Documents