Friday, April 10, 2009

Landscape - Scale Insects: Oystershell Scale

This is the eighth in a series on scale insects in the landscape. This post is on the Oystershell Scale. Information is from the University of Maryland.

Oystershell Scale (Lepidosaphes ulmi (Linnaeus)), Family Diaspididae

Plants Damaged: This scale is a general feeder (polyphagous) and is reported on 85 host plants in 33 families. We have observed it commonly on Acer (maples), Amelanchier (serviceberry), Cercis (redbud), Crataegus (hawthorn), Quercus (oak), and Prunus spp., but is found on many additional species.

Damage Symptoms: Yellowing of foliage and dieback of branches.

Life Cycle: There are univoltine and bivoltine forms found in Maryland. Bivoltine forms have crawlers present in April. Crawlers of the univoltine form are present from May through June.

Monitoring: The adult females of this armored scale look like elongated oysters.

Control: Horticultural oil or Distance at crawler emergence.

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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