Wednesday, July 1, 2009

Landscape - Juniper Scales

The following is information on Juniper scales that have been hatching in the landscape.

Juniper Scale

This imported armored scale insect is found on the foliage and twigs of juniper (occasionally arborvitae). The female covers are circular and white (1/16 inch in diameter); the male covers are white and elongated and are even smaller in size. With light infestations there is often no apparent symptoms. Significant populations of 10 or more scales per ½ inch of twig can result in yellowed foliage and needle drop. Dieback can occur with high populations. Scales usually build up first on the south side of shrubs or on the side against buildings. Adult females over-winter on the foliage and there is only one generation each year. Crawlers start hatching by mid-June and can continue well into July.

Controls may not be required if many beneficials are present (monitor for parasitoid exit holes in covers and for dustywings and ladybeetles). Dormant oil sprays can be used and summer oils or insecticidal soaps can be targeted against the crawlers. A late summer systemic insecticide such as acephate (Orthene) can be applied if the crawler stage is missed.

Juniper scale. Photo by United States National Collection of Scale Insects Photographs Archive, USDA Agricultural Research Service,

Information from Steven K. Rettke, Ornamental IPM Program Associate, Rutgers University in the June 11, 2009 edition of the Plant and Pest Advisory, Landscape, Nursery and Turf Edition from Rutgers University

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