Common Name: Brown soft scale, lecanium scale
Scientific Name: Coccus hesperidum Linnaeus, Lecanium sp.
Description: Adults are oval, flattened, slightly convex, reddish-brown scale insects. Immature scale insects (second instar) resemble adults but are smaller, except for the mobile crawler stage which has three pairs of legs, is pinkish, oval in shape and has two prominent hairs (setae) arising from the end of the abdomen.
Members of the Coccidae family are also called “soft scales” or coccids, and include wax scales and tortoise scales. Lecanium scales (Lecanium sp.) are common soft scales on a wide range of woody ornamental plants and fruit trees. The adult female scales are usually brownish, oval to round and about 1/4 inch in diameter. Scales in the family Diaspididae are called “armored scales” and their scale covering can be removed because it is usually free from their bodies.
Life Cycle: Intermediate. Eggs are produced within the female and hatch into first stage nymphs, or crawlers, when they are laid. Crawlers disperse and find a suitable feeding site within a few days. After about a week, they molt into the second stage, passive nymph. Winged adult males and females emerge in about a month. Six to seven generations can occur per year indoors.
Habitat, Food Source(s), Damage: This scale insect feeds on a wide variety of ornamental foliage and flowering plants, particularly ferns. Removal of sap from host plants causes plant stress, and the sweet liquid, called honeydew, coats the surfaces on infested host plants. A fungus called sooty mold colonizes the honeydew and causes the surface to turn black. As a result, heavily infested plants become unsightly and often loose their leaves. Shady new leaf and stem growth is preferred as sites for infestation.
Pest Status: Common and frustrating pest of house plants and indoor plantscapes; occasionally found outdoors; medically harmless.
Literature: Carter et al. 1982.