Two palm tree weevils found in California have some nursery stock producers and date growers on edge over the potential spread of the pests and how possible quarantines could jeopardize future plant shipments.

The pests include the red palm weevil (RPW), Rhynchophorus ferrugineus, and the South American palm weevil (SAPW), Rhynchophorus palmarum. The weevils are economic threats to California’s palm nursery and date industries.

Red palm weevil

Last August, agriculture officials confirmed the first U.S. detection of the RPW in a dying Canary Island date palm at a residence in Laguna Beach (Orange County). The palm was safeguarded, removed, quartered, examined, and destroyed.

The weevil, native to Southeast Asia, is considered the worst palm tree pest in the world.

The most shocking impact from weevil feeding occurs when the tree top falls over. Other symptoms include droopy, smaller and yellowed palm leaves. Tunnels and brown fluid are found at base of the frond petiole.

The RPW is attracted to unhealthy palms, but also attacks healthy palms. Primary hosts include 24 species of palm.

The female RPW bores into the palm tree laying up to 250 eggs over a lifetime. The eggs hatch in about three days. The voracious larvae feed in the apical growing point of the palm reducing the ability to transport nutrients and water to the crown. Reddish-brown adults are 1.4 to 1.6 inches in length.

The California Department of Food and Agriculture has placed 144 traps in Orange County; most in the Laguna Beach area. The pheromone bucket traps are checked weekly.

There have been reports of additional RPW finds in the same area which would normally trigger a USDA-Animal and Plant Health Inspection Service (APHIS) quarantine.

Larry Hawkins, APHIS spokesman in Sacramento, Calif., says a single insect was found in the initial find in Laguna Beach by agriculture officials. Other RPW insects found by residents were hand-delivered to agriculture officials. Hawkins says those insects do not officially count to APHIS. Officials must capture an insect on or inside the palm tree to be declared an official detection.

“The federal order (quarantine) trigger for this insect would be finds of two insects of any life stage (either sex) within one life cycle within 3 miles distance of each other,” Hawkins said. “We haven’t met the trigger. We officially only have one insect.”

APHIS has prepared a draft quarantine document in case other RPWs are found.

If the official RPW trigger is met, Hawkins says the quarantine would likely include restrictions on the movement of host material and waste products, plus an inspection of nursery palms grown for shipment.