The Diaprepes Root Weevil (Citrus Root Weevil)
This weevil appears to have the potential to do major damage to roses. The information below was published by the University of California, Division of Agriculture and Natural Resources.
The Diaprepes root weevil, Diaprepes abbreviatus (L.) (Coleoptera: Curculionidae), is a large, colorful weevil, 3/8 to 3/4 inch (10 to 19 mm) long, with numerous forms, or morphs, ranging from gray to yellow to orange and black (fig. 1). This weevil is native to the Caribbean region and was accidentally introduced into Florida in the 1960's where it has caused extensive damage. It has been intercepted in shipments of plants to California and in 2005 two isolated populations were found in Newport Beach (Orange County) and Long Beach (Los Angeles County). The California Department of Food and Agriculture has established quarantine zones in Newport Beach and Long Beach to control this pest and prevent it from spreading.
This weevil will feed on about 270 different plants including citrus (all varieties), hibiscus, palm, birch, roses, guava, loquat, holly, and other ornamentals. Because of its broad host range, the Diaprepes root weevil poses a great threat to citrus and ornamental plant industries in California.
The Diaprepes root weevil damages both the leaves and the roots of plants. The adult weevils damage leaves by chewing semi-circular areas out of the leaf margin (fig. 2). There may also be frass or weevil droppings near the areas that have been fed upon. The grub-like larva feeds upon the roots of a plant weakening or killing a plant.
An adult female weevil lays clusters of eggs in leaves that are folded and glued together (fig. 3). The eggs hatch in 7-10 days, and the newly emerged larvae drop to the soil (fig. 4). The larvae enter the soil and feed upon the roots of plants for several months. The larvae then pupate in the soil (fig. 5). After the appropriate amount of time, adults will emerge and the life cycle begins again.
If you see the adult weevils or have damage to plants you suspect is caused by the weevil, please contact the CDFA Exotic Pest Hotline at 1-800-491-1899. Personnel from CDFA will inspect plants for the presence of the Diaprepes root weevil and send any specimens collected to the CDFA diagnostic laboratory for identification.
For more information, read Publication 8131: Diaprepes Root Weevil (free) found on the University of California Division of Agriculture and Natural Resources publications website: anrcatalog.ucdavis.edu.
Fig. 1 – Diaprepes Root Weevils
Fig. 2 – Frass left by feeding adults
Fig. 3 – Diaprepes eggs about .04 inch long
Fig. 4 – Diaprepes larva
Fig. 5 – Pupal stage of Diaprepes