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How to Manage Pests

UC Pest Management Guidelines

Adult branch and twig borer, Melalgus (=Polycaon) confertus, on grape shoot.


Branch and Twig Borer

Scientific name: Melalgus (=Polycaon) confertus

(Reviewed 6/06, updated 6/06)

In this Guideline:


The branch and twig borer is a slender brown beetle about 0.5 to 0.67 inch long. The body is cylindrical and the head and prothorax are narrower than the body proper. The beetle lays its eggs in the dead wood of a number of native and cultivated trees and shrubs outside the orchard or on dead prune limbs once an orchard becomes infested. Larvae bore into the heartwood of the host and feed for a year or longer. Pupation occurs within the wood and adults emerge in early summer. They often fly from native vegetation to orchards where they bore into small branches on the trees. There is one generation per year.


The adults bore into small twigs and branches, making round holes, commonly at the axil of a bud or fruit spur or at the fork of two branches. One of the branches frequently dies. Branch and twig borers seldom cause economic injury and are found only rarely in prunes.


These beetles do not prefer healthy, vigorous growing trees. Maintain a program of sunburn protection and proper irrigation and fertilization. Promptly destroy brush piles harboring these pests. Remove prunings and brush piles from orchard in the early spring. Remove badly infested trees and branches from the orchard and shred or haul them to the dump. There is no insecticide treatment currently recommended to control the larvae of these borers.


[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Prune
UC ANR Publication 3464
Insects and Mites
C. Pickel, UC IPM Program, Sutter/Yuba counties
F. J. A. Niederholzer, UC Cooperative Extension, Sutter/Yuba counties
W. H. Olson, UC Cooperative Extension, Butte County
F. G. Zalom, Entomology, UC Davis
R. P. Buchner, UC Cooperative Extension, Tehama County
W. H. Krueger, UC Cooperative Extension, Glenn County
Acknowledgment for contributions to Insects and Mites:
W. O. Reil, UC Cooperative Extension Solano/Yolo counties

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