Tuesday, April 14, 2009

Landscape - Scale Insects: Calico Scale

This is the 12th in a series on scale insects in the landscape. This post is on the Calico Scale. Information is from the University of Maryland.

Calico Scale (Eulecanium cerasorum), Family Coccidae

Plants Damaged: Calico scale is a general feeder and can be found on many nursery and landscape plants including dogwood, honeylocust, magnolia, maple, sweet gum, tuliptree and ornamental fruit trees.

Damage Symptoms: Calico scale covers the branches and leaves of the host plant and feeds on the phloem tissue. The plant may be covered in sooty mold as a result of the large quantities of honeydew produced by the calico scale. In large numbers, feeding can result in branch dieback.

Identification: This white and dark brown calico scale is about 1/4 inch in diameter and is brightest when it reaches maturity and then darkens. First-instar nymphs start out pinkish and become yellowish as they enlarge. Overwintering Immature females are oval, flattened, and light to dark brown and have a hard waxy coating. Just before egg hatch the covering is white with gray-blue patterns.

Life Cycle: This scale overwinters as second instars and molts and matures to 3rd instars in early spring. The nymphs of this scale will migrate out onto the foliage in June and feed through the summer. In the fall the immatures will migrate back to the twigs where the females overwinter.

Monitoring: Look for copious amounts of honeydew in late May and early June. Look for the oval-shaped, yellow-bodied crawlers in June.

Control: Apply horticultural oil in March to early April to kill overwintering females. When crawlers are out, use 1% horticultural oil or Distance. Another option for controlling soft scale is to use a soil injection or soil drench of a systemic insecticide, such as imidacloprid or dinotefuran. This material takes 30 - 60 days to be taken up by the plant before it begins to control the scale. It is very effective against soft scale insects such as calico scale.

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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