This soft scale feeds on crabapple, sweetgum, star magnolia, honey locust, maple, dogwood, elm, oak, pear, redbud, tulip tree, all stone fruit trees, and many other species of trees.

Figure 1: Calico Scale. Raymond Gill, California Department of Food and Agriculture, Bugwood.org and Figure 2: Calico Scale. United States National Collection of Scale Insects Photographs, USDA Agricultural Research Service, Bugwood.org

Identification

Adult female scales have distinctive white and black coloration and turn dark brown with age. Females are approximately 6-8 mm. Crawlers are pinkish-white in color. Nymphs are flattened and gray in color. They cover themselves with a waxy cuticle, which protects them from pesticide applications.

Biology

During the spring females swell, and they lay eggs during May. They produce large deposits of honeydew, a sugary fecal liquid, because they remove sap and other sugary fluids from the tree. Honeydew can give the plant a shiny appearance, and is frequently colonized by sooty mold fungus. Heavy infestation can result in premature leaf drop, stunt in growth, branch dieback, and plant death. Females turn brown and die right before the crawlers hatch from the eggs around 519—902 (676 peak) GDD50. The plant phenological indicator, Syringa pubescens ssp. Patula ’Miss Kim’ in full bloom, maybe used to also indicate crawler activity on host trees. Crawlers settle near the veins of foliage and begin to feed until they move back to twigs or sheltered areas on the bark during mid-September to over- winter as nymphs. Calico scale has one generation per year.

Management Strategies

Chemical control is an effective method of management for this scale. Applications should target crawlers when they are active, and before they settle down on the plant. A non-chemical method of control is hand scraping the females off of tree branches. Contact a local cooperative extension office for insecticide recommendations for this scale species.

Figure 3: Calico Scale. United States National Collection of Scale Insects Photographs, USDA Agricultural Research Service, Bugwood.org

References

Davidson, J.A., Raupp, M.J. (2009). Managing Insects and Mites on Woody Plants: an IPM Approach. Tree Care Industry Association.

Fulcher, A., Bowers, H. (July 2011). Calico Scale. University of Tennessee Department of Plant Sciences.

Hoover, G.A. (2011). Woody Ornamental Insect, Mite, and Disease Management. Pennsylvania State University College of Agricultural Sciences.

Hubbard, J.L., and D.A. Potter. 2006. Managing Calico Scale (Hemiptera: Coccidae) Infestations on Landscape Trees. Arboriculture & Urban Forestry 32(4): 138-147

Images: Bugwood.org

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