Coccus hesperidum L.
Taxonomic placing: Insecta, Hemimetabola, Hemiptera, Sternorrhyncha, Coccomorpha, Coccoidea, Coccidae.
Common name: Brown soft scale.
Geographical distribution: Cosmopolitan; living outdoors in tropical and subtropical regions, indoors in temperate climates. CIE Map #92 (revised), 1972.
Host plants: Polyphagous.
Morphology: The brown, elliptical and flattened body of the female is 3.0-5.0 mm long and its shield may bear randomly dispersed reddish spots. Short, spine-like setae are located all over the body; antennae usually with 7 segments and the anal plates form a quadrate, each half bearing four short posterior setae.
Life history: The pest is parthenogenetic, each female laying about 75 eggs, and it usually completes 6 annual generations. The calculated threshold of development is at 13ºC and 515 day-degrees are necessary for the completion of a generation. The scale is often attended by ants that protect it from some of its more efficient natural enemies. Short dsitance dispersal by the crawlers is by walking, dispersal between host plants is by being borne on winds.
Economic importance: Damage (especially to young citrus trees is mostly due to secreting large amounts of honeydew that is colonized by sooty mold fungi, covering fruits and leaves by a thick black mass. Coccus hesperidum was considered a major pest of citrus in Israel before being completely controlled by its natural enemies.
Chemical control: Applications of mineral white oils, aimed at the scale’s young stages, control the pest without affecting its natural enemies.
Biological control: The brown soft scale is usually controlled by a suite of endoparasitoids. Sparse pest populations are controlled by the encyrtid Microterys nietneri, whereas Coccophagus spp. (Aphelinidae) are dominant in ant-attended scale colonies. Another encyrtid, Metaphycus flavus_, is sensitive to ant presence and may be replaced by the ant-tolerant Coccophagus spp. Additional parasitoids are associated with this pest in the Middle East. However, the biological control of this pest be reduced at times by its ability to encapsulate the parasitoid eggs.
Abd-Rabou, S., Hanafi, A. and Hussein, N. 1999. Notes on the parasitoids of the soft brown scale, Coccus hesperidum (Hemiptera: Coccidae) in Egypt. Entomologica 33: 179-184.
Blumberg, D. 1977. Encapsulation of parasitoid eggs in soft scales (Homoptera: Coccidae). Ecological Entolology 2: 185-192.
Hoelsche, C.E. 1967. Wind dispersal of brown soft scale crawlers Coccus hesperidum (Homoptera – Coccidae) and Texas citrus mites Eutetranychus banksi (Acarina – Tetranychidae) from Texas citrus. Annals of the Entomological Society of America 60: 673-678.
Mohamed, E.M., Basher, A.M. and Abukaf, N. 2013. Survey of parasitoid species associated with the brown soft scale iInsect, Coccus hesperidum L. (Homoptera: Coccidae) on citrus trees at Lattakia, Syria. Egyptian Journal of Biological Pest Control 23: 25-29.
Rosen, D. 1967. On the relationship between ants and parasites of coccids and aphids on citrus. Beiträge für Entomologie 17: 281-286.
Swirski, E., Wysoki, M. and Izhar, Y. 2002. Subtropical Fruits Pests in Israel. Fruit Board of Israel (in Hebrew with an English Summary).