How to Manage Pests

Pests in Gardens and Landscapes

Branch and twig borers—Scobicia declivis, Polycaon confertus

Adult borers are dark brown beetles, cylindrical in shape and 0.25 to 0.5 inch long. The immature stage (grub) is white, fleshy, enlarged just below the tiny head, and appears legless. It is typically curled up in a C-shape.

Life cycle

Damage

Larvae tunnel in twigs causing dieback. Adults bore into small twigs commonly at bud or spur axils to lay eggs. This causes twigs or branches to die and leaves to wilt, resembling a blight strike from disease. If a hole is present, the damage is caused by the borer.

Solutions

Keep plants vigorous by providing proper cultural control. Prune out dying and dead parts of the tree and remove or burn all prunings before March, because these are breeding sites for beetles. Keep area free of prunings and wood cut from ornamentals. Pesticides should not be necessary.

Branch and twig borer adult
Branch and twig borer adult

Hole in twig from borer
Hole in twig from borer


Statewide IPM Program, Agriculture and Natural Resources, University of California
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