Agriculture: Floriculture and Ornamental Nurseries Pest Management Guidelines

Common Signs and Symptoms on Plants Damaged by Pest Insects, Mites, Slugs, and Snails (Arthropods) and the Probable Causes

Symptoms Causes
arthropod by-products
bleached, bronzed, stippled, or yellowed foliage
chewed or tattered blossoms or foliage
  • adults and larvae of leaf-feeding beetles
  • crickets, grasshoppers, or katydids
  • larvae (caterpillars) of butterflies and moths (Lepidoptera) e.g., armyworms, cabbage looper, cutworms, diamondback moth, European pepper moth (Dufo moth)
  • larvae of sawflies (broad-waisted wasps) e.g., rose slugs
  • leafcutting bees, which are important pollinators and should not be killed. Where these bees have been collecting material for their nests covering those plants with cheesecloth or other screening prevents further damage. Place out these barriers when leaf cutting is first observed or the time of year (late winter or spring) when damage first occurred during previous seasons. Barriers can be removed about midsummer when the mother bees are no longer active.
  • snails or slugs e.g., brown garden snail
dieback of plant parts
distortion of plant parts
foliage mines
  • larvae of certain flies, moths, or sawflies (broad-waisted wasps)
holes in stems, bark or twigs
  • adult beetles e.g., bark beetles, flatheaded borers, longhorned beetles
  • larvae of boring beetles or caterpillars (e.g., clearwing moths) feeding hidden in plants
Adapted from Container Nursery Production and Business Management Manual, UC ANR Publ. 3540
Text Updated: 03/21