How to Manage Pests

Pests in Gardens and Landscapes

Juniper twig girdler—Periploca nigra

The juniper twig girdler adult is a small, shiny, brownish black moth. The adult is not often seen. Mature larvae are cream colored with brown heads.

Identification of species

Damage

The smaller limbs of infested junipers become yellow, then turn brown and die. This branch "flagging" is most apparent in the late summer and causes a checkerboard of green and brown limbs and retarded plant growth. Under the twig bark, larvae and the characteristic girdling tunnels can be seen. Twig girdler feeding does not kill entire juniper plants.

Solutions

To improve plant appearance, prune out and dispose of affected branches. Tam juniper, Juniperus sabina 'Tamariscifolia', is extremely susceptible to damage; avoid planting this variety and consider replacing existing plantings with more resistant junipers. Hollywood junipers, J. chinensis 'Kaizuka' or 'Torulosa', are resistant to juniper twig girdler attack. If damage cannot be tolerated, thoroughly spray foliage with a persistent insecticide such as permethrin twice annually. Spray about late March and early May in Southern California and early June and middle July in Northern California. Insecticide kills adult moths and prevents them from laying eggs, but boring larvae are not affected and spraying does not restore the appearance of damaged foliage, which remains brown until new growth occurs.

Dead patches
Dead patches caused by Juniper twig girdlers


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

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