Tuesday, April 28, 2009

Landscape - Scale Insects: Obscure Scale

This is the 20th in a series on scale insects in the landscape. This post is on the Obscure Scale. Information is from the University of Maryland.

Obscure Scale (Melanaspis obscura), Family Diaspididae

Plants Damaged: Obscure scale is an armored scale found on many pin oaks in the landscape, but is also found on a few other species of oak such as white oak. It has been reported on grape, dogwood, walnut, Prunus spp, pecan and hickory.

Damage Symptoms: Yellowing of foliage and dieback. Life Cycle: The obscure scale has one generation per year in Maryland. Second instar male and females overwinter and mature in spring in May. Eggs are laid in late June and July. Crawlers are present from July through early September. Stoetzel and Davidson (1973) found that this scale on white oak was one month behind its development on red oak.

Monitoring: Adult female covers are circular and gray to black in color. The scales are usually crowded together and overlap each other on the branches and sometimes in the trunks of trees.

Control: Horticultural oil or Distance at crawler emergence. The crawlers should be active in central Maryland by the end of June.

Photo by James Solomon, USDA Forest Service, Bugwood.org

Information from "Scales Commonly Encountered in Maryland Landscapes and Nurseries" by Stanton Gill, Extension Specialist in IPM for Nurseries and Greenhouses,and Suzanne Klick and Shannon Wadkins, Technicians, Central Maryland Research and Education Center University of Maryland Cooperative Extension.

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