General Information
Living adult female brown soft scales, Coccus hesperidum, are pale yellowish-green to yellowish brown, often mottled with brown spots. Older females are brown. The body is usually oval in outline, up to 3⁄16 inch in length and slightly convex in profile. The shape tends to vary according to position on the host plant. Males are rare, but resemble tiny wasps or flies.
Crawlers and young nymphs are yellow and almost flat in profile. Parasitized nymphs are dark brown to black and convex. Crawlers have well developed legs and antennae and are crawl about actively before settling. Older nymphs are sessile.
Biology
Brown soft scale is cosmopolitan in tropical and subtropical regions and in greenhouses in northern regions. In North America it occurs out of doors in the deep South, and north along the eastern seaboard to Virginia, and as far north as southern Vancouver Island on the west coast.
Brown soft scale has been reported feeding on hundreds of different plants. It can survive on most greenhouse plants, but seems to prefer perennials to annuals. Ferns are a favored host.
Brown soft scale is a frequently encountered scale on plants indoors. Infestations of brown soft scale can become so heavy as to encrust the stems and petioles of their host plant. They also settle on leaves, usually along midribs and occasionally on the fruit. Large colonies remove large quantities of plant fluids and can cause wilting, but they seldom kill their host. Immatures and adults produce much honey dew that serves as a medium for the growth of sooty molds. These fungi inhibit photosynthesis and make infested plants unsightly. Obnoxious insects such as ants and wasps are also attracted to feed on the honeydew.
Females retain their eggs in the body until hatching. Brown soft scales are born as active crawlers but remain under the body of the female for a short time before emerging and selecting a feeding site to settle and complete their development. Females molt twice before reaching maturity. Males undergo four molts before emerging as winged adults, but are rarely seen. All stages are found throughout the year in warmer regions and in greenhouses. Brown soft scales can complete three to seven generations per year depending on temperature. It takes about 60 days to complete a generation.
Brown soft scale (A) adult (B) crawler.
Brown soft scale insects are flattened and mottled brown.
Female brown soft scale insects are slightly convex and up to 3⁄16 inch long.
Control
Brown soft scales are surprisingly difficult to control even though there is no external egg stage, and only the body of the mother protects a few very young nymphs at any one time. Although reported as a pest species of many host plants in many countries, outdoors natural enemies in many areas may suppress it. Scutellista cyanea Motschulsky is a common parasite and Metaphycus luteolus Timberlake controls brown soft scale in California.
The following pesticide formulations should control brown soft scales if applied to infested plants thoroughly. A second application may be necessary. Wait about 10 days between applications. Never set an ornamental plant out in the sun to treat it. Pesticide injury may result. Keep treated plants in the shade or treat during the cooler parts of the day so the foliage will dry before the plant is exposed to direct sunlight.
| Pesticide | (Trade Name) | Formulation and Amount |
|---|---|---|
| acephate | (Orthene*) | 9.4% emulsifiable concentrate. Outdoors only. 3 tablespoons per gallon of water. |
| acephate | (Orthene) | 75% soluble powder. 2⁄3 pound per 100 gallons of water. |
| azadirachtin | (Azatin, BioNeem*) & others | 3% emulsifiable concentrate. 1⁄2 teaspoon per gallon of water. |
| cyfluthrin | (Decathlon) | 20% wettable powder. 1.9 ounces per 100 gallons of water. |
| dinotefuran | (Safari) | Spray or soil drench. |
| fenoxycarb | (Precision) | 25% wettable powder. 1⁄2 teaspoon per gallon of water. |
| imidacloprid | (Marathon) | 60% wettable powder. Greenhouses and nurseries. Apply as drench. |
| imidacloprid | (Merit*) | 75% wettable powder. Landscapes and interiorscapes. Apply as drench. |
| kinoprene | (Enstar II) | 65.1% emulsifiable concentrate. 5 to 10 ounces per 100 gallons of water. |
| lambda-cyhalothrin | (Scimitar GC) | 10% water soluble packets. 2 to 4 packets per 100 gallons of water. |
| malathion* | 50 to 57% emulsifiable concentrate. 2 teaspoons per gallon of water. | |
| oil (horticultural or summer)* | various | 98 to 99% emulsifiable concentrate. 8 teaspoons per gallon of water. |
| pyrethrins* | (Pyrenone & others so labeled) | 6% emulsifiable concentrate. 1⁄8 to 11⁄2 teaspoons per gallon of water. |
| soap* | (M-Pede, Olympic, Safer's) | 50.5% emulsifiable concentrate. 2 to 5 tablespoons per gallon of water. |
| * Suitable for home use. When used as directed, pyrethroids are very toxic to insects but are not particularly hazardous to humans and pets (other than fish—avoid using pyrethroids around pools, ponds, and streams). | ||
Other Resources
- Brown Soft Scale. In A Field Guide to Common Texas Insects. Drees, B. M. and J. Jackman. 1999. Texas A&M Agrilife Extension, Entomology.
- Insect and related Pests of Flowers and Foliage Plants. Baker, J. R., ed. 1994. N.C. Cooperative Extension publication AG-136. 106 pp.
- Selected Scale Insect Groups (Hemiptera: Coccoidea) in the Southern Region of the United States. Miller, D. R. 2005. Florida Entomologist, 88(4) : 482-501
- Coccus hesperidum (Linnaeus) J. L. M. Kessing, J. L. M.. R. F.L. Mau and J. M. Diez. 2007. Department of Entomology, University of Hawaii, Honolulu.
- NC State Horticultural Science Publications
- NC State Extension Plant Pathology Publications
- North Carolina Agricultural Chemicals Manual
For assistance with a specific problem, contact your local N.C. Cooperative Extension center.
Publication date: April 1, 1998
Revised: Nov. 21, 2020
Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by NC State University or N.C. A&T State University nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your local N.C. Cooperative Extension county center.
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