The Diaprepes Root Weevil in San Diego County

The Diaprepes (die-a-prep-ees) root weevil (Diaprepes abreviatus), also called the citrus root weevil or the West Indian sugarcane root borer has been found in several areas of San Diego county – La Jolla, University City, Encinitas, Carlsbad, Del Mar, Carmel Valley, Fairbanks Ranch, Rancho Santa Fe and Oceanside. It's a large, colorful weevil, three- eighths to three-quarters of an inch long, with numerous color forms ranging from gray to orange with black stripped markings.

Originally from the Caribbean, it was accidentally introduced into Florida in 1964 in an ornamental plant shipment from Puerto Rico, and has since caused serious damage to citrus trees. Diaprepes has been intercepted a number of times in California since 1974 in shipments of plants and all of these interceptions have been destroyed. In the fall of 2005 all that changed. A Diaprepes root weevil was found in a residential neighborhood of Newport Beach, making it the first detection and quarantine for the weevil in California.

In April 2006, the weevil was also found in the University City of San Diego County. The California Department of Agriculture (CDFA) initiated a survey and after confirming the weevil was present in the environment and delimiting the size of the infestation, our first quarantine in San Diego was declared.

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Why is this weevil so bad?

  • The weevil feeds on more than 270 species of ornamental and agricultural plants and list keeps on growing. A few of its favorite plants are palms, roses, hibiscus, Indian hawthorn, bougainvillea, coral trees, citrus, privet, trumpet vine, and Brazilian pepper.
  • Two life forms of this insect can damage plants. The adults eat the leaves and the larvae or grub feeds on the plant’s roots. Larval damage can often go unnoticed until the plant is dying and then it is too late. Root damage also provides a pathway for other plant diseases that can harm or kill the plant.
  • The weevil can live 18-24 months. The length of the life cycle depends on soil moisture and temperature. The larvae can live 8 to 15 months in the soil and the adults can live up to 5 months.
  • One female will lay about 5,000 eggs in her lifetime.
  • There isn’t a good trap or attractant for the weevil.
  • The weevil is a good hitchhiker.

What is being done?
CDFA has set up quarantine areas around the weevil-find sites to prevent the movement of the weevil to other areas. Since the weevil is a great hitchhiker, this means controlling the movement of green waste such as tree prunings, shrub cuttings and ground cover plants where the adult weevils like to hide and feed. Grass clippings are exempt and not regulated. Residents and yard maintenance companies working in these quarantine areas are asked to:

  • Place plant material in double plastic bags and place the bags in their regular waste bins for pick-up by their local commercial waste company.
  • Place plant material in their green waste recycling bins for closed transport to the landfill or recycling center by their local commercial waste company.
  • Chip or shred prunings or cuttings.
    If a homeowner or the hired yard maintenance company wants to transport plant material to a green waste recycling center or landfill themselves, they must transport all plant material in an enclosed vehicle or cover the plant material in an open truck or trailer with a tightly fitted solid tarp or burlap so nothing can blow out.
Besides stopping the movement of the weevil, eradication efforts are underway with CDFA coordinating targeted pesticide treatments. Agricultural experts from Florida, University of California, UC Cooperative Extension, CDFA and the agricultural industry are working together to make sure the weevil does the least impact to our agriculture and residents.

Any good news?
  • The weevil doesn’t like to move much. Once it takes up residency in a bush or tree it likes to stay there. This makes eradicating it much easier.
  • The weevil is harmless to man or pets.

What can you do to protect California’s agriculture and ornamental plants?
Look for the Diaprepes root weevil in your yard. Check your plants for feeding damage. Typical damage done by the adult is semi-circular notching along the leaf edges. Other insects may leave similar damage, primarily the Fuller rose weevil, a small gray weevil about three-eighths of an inch long. One way to be certain of which insect is responsible for the leaf damage is to shake the branch or plant with the damaged foliage over a light-colored cloth or an opened umbrella. Collect any weevils and report them to the CDFA's Exotic Pest Hotline number at 1-800-491-1899. A representative can answer questions and send an official out to collect the insects for identification.

For more information on the Diaprepes root weevil go to CDFA’s website at www.cdfa.ca.gov/phpps or San Diego county’s website at www.sdcounty.ca.gov/awm/ For more information on the rules and regulations of the quarantine and maps of the quarantine areas go to http://pi.cdfa.ca.gov/pqm/manual/htm/417.htm.