How to Manage Pests

UC Pest Management Guidelines


Branch and Twig Borer

Scientific name: Melalgus (=Polycaon) confertus

(Reviewed 9/16, updated 9/16)

In this Guideline:


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.


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.


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.


[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Avocado
UC ANR Publication 3436


J. G. Morse, Entomology, UC Riverside
B. A. Faber, UC Cooperative Extension, Santa Barbara/Ventura counties
M. S. Hoddle, Entomology, UC Riverside

Acknowledgment for contributions to Invertebrates:
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
M. Blua, Entomology, UC Riverside
P. Oevering, UC Cooperative Extension, Ventura County
D. Machlitt, Consulting Entomology Services, Moorpark, CA
T. Roberts, Integrated Consulting Entomology, Ventura, CA
B. B. Westerdahl, Nematology, UC Davis

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