Citrus Pest Quick Guide: Brown Soft Scale (Coccus hesperidum Linnaeus)1

Lauren M. Diepenbrock and Jamie D. Burrow 2

Life Cycle

Immature brown soft scale hatch as crawlers, then settle to feed. Young soft scales can relocate when disturbed.

Brown soft scale is flat and oval during larval and adult stages with color ranging from yellowish to light brown. Color becomes darker as the scale ages, and its outer covering becomes tougher.

Populations of brown soft scale are generally found on leaves and twigs with occasional infestation on fruit. Brown soft scale populations tend to be clumped together due to their high reproductive capacity. Three to five overlapping generations have been recorded in citrus.

Figure 1. Brown soft scale.
Figure 1.  Brown soft scale.
Credit: L. Buss, UF/IFAS

Figure 2. Brown soft scale on citrus.
Figure 2.  Brown soft scale on citrus.
Credit: L. M. Diepenbrock, UF/IFAS

Figure 3. Darker scales are parasitized.
Figure 3.  Darker scales are parasitized.
Credit: L. Buss, UF/IFAS

Figure 4. Parasitized brown soft scale. Holes indicate where a parasitoid has emerged.
Figure 4.  Parasitized brown soft scale. Holes indicate where a parasitoid has emerged.
Credit: L. Buss, UF/ IFAS

Damage

Brown soft scale excretes large quantities of honeydew (sugary solution) while feeding, which provides a substrate for sooty mold to develop. Sooty mold can cover leaves and fruit, reducing photosynthetic capabilities of trees. In older plantings, this feeding can result in reduced tree vigor, twig dieback, and reduced fruit quality and/or yield. In younger plantings and nursery stock, these scales and the resulting honeydew accumulation can sometimes cause tree death.

Figure 5. Colony of brown soft scale with crawlers, adults, and parasitized adults present.
Figure 5.  Colony of brown soft scale with crawlers, adults, and parasitized adults present.
Credit: L. Buss, UF/IFAS

Figure 6. Sooty mold growing on honeydew excreted by scales.
Figure 6.  Sooty mold growing on honeydew excreted by scales.
Credit: M. E. Rogers, UF/IFAS

Footnotes

1. This document is ENY-2039, one of a series of the Entomology and Nematology Department, UF/IFAS Extension. Original publication date February 2020. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication.
2. Lauren M. Diepenbrock, assistant professor, Entomology and Nematology Department; and Jamie D. Burrow, Extension program manager; UF/IFAS Citrus Research and Education Center, Lake Alfred, FL 33850.