Fall Webworm on Rosemary: Biological Control with Dipel

Three 10-year-old, 4-ft rosemary bushes in LA County covered daily with white webs; light brown moths fly out; hosing ineffective.

Identification

Fall webworms—caterpillars making webs on branch tips, feeding at night. Webs block spray penetration. Moths are adults.

Dipel (Bacillus thuringiensis)—biological, effective on caterpillars, safe for edibles. Check nursery. Avoid chemical pesticides on culinary herbs.

Plant Diseases: Forsythia Dieback: Stem Splits, Borers, and Wet Soil Management; Identifying and Controlling Spittlebugs on Rosemary; Webs on Bushes: Spiders or Webworms?; Oak Tree Webbed Clumps: Fall Webworms, Minor Pest; Rose Bushes Summer Yellowing: Black Spot on Grafted Roses; Burning Bush Trouble? Check for Insects, Not Fertilizer pH; Spider Mites on Holly: Webbing and Leaf Damage Control; Protecting Roses from Late Frost; Large Rosemary Bushes: Pruning for Size and Shape; Reviving Browning Rosemary Bushes: Causes and Solutions

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