Calico Scale Diagnostic Guide
Calico scale, Eulecanium cerasorum is a pest of variety woody plants. Introduced into the San Francisco area in the early 1900’s, it has continued to spread throughout the Pacific Coast states and several eastern states, including Pennsylvania, Maryland, Delaware, Virginia, and Long Island. Calico scales produce large amounts of honeydew in the spring which can coat tree leaves, branches, sidewalks, and cars. This sticky sap soon turns black from sooty mold fungi growing on it and in severe cases may interfere with the trees ability to photosynthesize, making it more susceptible to woodborers, drought, and other stresses.
Trees at Risk
Calico scale can be a pest on all stone fruit and ornamental fruit trees, elm, maple, zelkova, honeylocust, sweetgum, magnolia, buckeye, pyracantha, tuliptree, dogwood, and Boston ivy.
Signs of Damage
- Large amounts of honeydew in the spring.
- Sooty mold fungi growing on the honeydew.
- Stunted, yellowing leaves leading to premature leaf drop.
- Dead branches and stunted twig growth.
- Large dark brown and white globular scale about 1/4” in diameter on twigs and branches in May and June.
- Presence of tiny pink crawlers on the underside of leaves during summer.
The systemic insecticides Xytect™ and Transtect™ work very well for this scale. The only occasion for using sprays is during crawler emergence when immediate control is needed.
Properly timed applications of Xytect™ or Transtect™ will provide a high level of control for most calico scale. Dead adult scales may be visible for a year.
A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org