HYG  Pest newsletter

Issue Index

Past Issues

Scurfy Scale

July 10, 2002

Scurfy scale, Chionaspis furfura, eggs have hatched throughout Illinois and are looking for a "tasty morsel" to feed upon. Scurfy scale has a very wide host range; however, it primarily attacks plants in the rose family (Rosaceae), including hawthorn, quince, peach, crabapple, cherry, firethorn, and mountain ash. Other susceptible hosts include horsechestnut, elm, hickory, maple, willow, and dogwood. Scurfy scale is not a very common scale in Illinois, but there have been more reports of infestations in the last couple of years.

Female scurfy scales are flat, thin, grayish white, 1/8-inch long, and rounded on one side, which makes them appear pear- or oyster-shell-shaped. The females lay up to 80 eggs, which are distinctly reddish purple. They are retained under the female covering after she dies. The insect overwinters int he egg stage, with eggs hatching in late spring into purple crawlers that move around on plants and eventually locate a suitable place to settle and feed. Scurfy scale can be abundant on bark, giving a plant a "scurfy" appearance (hence the common name). The scale tends to be located on the shady side of trees or in areas under a dense canopy of leaves. Scurfy scale is a hard scale, so there is no honeydew produced during feeding. There are one to two generations per year in Illinois.

Scurfy scale in landscapes can be managed by applying pest-control materials when crawlers are active. Recommendations include acephate (Orthene), diazinon, insecticidal soap, and summer oil. Although many crawlers have settled down, reasonable control may still be possible. This scale is susceptible to dormant oil sprays during the winter.

Scurfy scale (like most scales) is susceptible to parasitoids (Aphytis spp.) and ladybird beetles; and, in sufficient numbers, these natural enemies may provide some level of control. The use of acephate, diazinon, and other persistent, broad-range insecticides is harmful to them and may disrupt natural control. Insecticidal soap and summer oil are less likely to harm parasitoid numbers.

Author: Raymond A. Cloyd


College Links