Monday, April 6, 2009

Landscape - Scale Insects: Euonymus Scale

This is the fourth in a series on scale insects in the landscape. This post is on the Euonymus scale. Information is from the University of Maryland.

Euonymus Scale (Unaspis euonymi (Comstock), Family Diaspididae

Plants damaged: Boxwood, camellia, and evergreen euonymus – especially Euonymus japonica.

Damage Symptoms: Yellowing of foliage and dieback of twigs and general thinning of infested plants.

Life Cycle: This armored scale overwinters as 3rd instar females. Crawlers appear in May and continue for 4 – 5 weeks. Second generation adults are out in July with crawlers present from August through September. The females are dark brown, oyster shell shaped and usually found on the stems. Males are smaller, white and mostly found on the leaves.

Monitoring: Look for chlorotic foliage with yellowing spotting or banding on the needles. Look for overwintering scale on the needles.

Control: A mixture of 1% horticultural oil and Distance does a great job of controlling this scale. Dinotefuran (Safari) applied as a soil drench also works well.

Euonymus scale. Photo from Clemson University - USDA Cooperative Extension Slide Series,

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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