Agriculture: Avocado Pest Management Guidelines

Branch and Twig Borer

  • Melalgus (=Polycaon) confertus
  • Description of the Pest

    The adult branch and twig borer (family Cerambycidae) is a slender brown beetle about 0.5 to 0.75 inches long. Its body is cylindrical, and the head and prothorax are narrower than the body. Females lay eggs in the dead wood of many different species of native and cultivated trees and shrubs. Larvae bore into heartwood and feed there for a year or more. Pupation occurs within the tree and adults emerge in early summer. There is one generation per year.

    Damage

    When present, borers cause a recognizable hole in branches. This entrance to a larval feeding tunnel often exudes sugary sap that turns white and flaky. Infested branches with tunnels can be easily broken by wind. Branch and twig borer is not common in avocado and seldom causes economic injury.

    Management

    Borers prefer injured, dying wood and stressed, slow-growing trees.

    • Protect trees from sunburn and injuries, such as by whitewashing exposed bark.
    • Provide appropriate irrigation to keep trees healthy.
    • Remove badly diseased or borer-infested trees and branches from the orchard. Promptly destroy brush piles. Branch and twig borers can emerge from cut limbs and attack nearby trees.
    • Spraying insecticides does not kill borer larvae because they are protected inside the branch. Consequently, pesticides are not recommended for this insect.
    Text Updated: 09/16