However, soft scales can be a nuisance long before there are any visible symptoms. A heavy infestation will cause yellowed leaves, distorted foliage especially at the growing tips, twig dieback, or defoliation. Soft scales are usually found on the undersides of leaves and stems, although some species may occur on upper leaf surfaces. They generally overwinter as immature, fertilized females.īrown soft scale on the underside of cycad leaves. Female soft scales don’t lose their antennae and legs completely, but are greatly reduced so although they can move, the adults seldom do. The waxy scale covering adheres tightly to the body of the female and cannot be separated from it. A waxy scale covering is produced over the female after she becomes an adult. The pale, newly hatched nymphs are the mobile crawler stage but after finding a suitable part of the plant they settle down for the remainder of their lives. Fifty to 2000 eggs or live young, depending on the species, are produced in or beneath the female’s body. Immature scales start out light in color and darken at maturity. Soft scales are round to oval, dome shaped, and 1/8 to 1/4 inch long when mature. The soft scales (Family Coccidae) are the more important of the two groups of scales found on indoor plants. The protective cover of the calico scale ( Eulecanium cerasorum), an invasive species, is readily apparent. There are two types of scales: the soft scales and the armored scales. Traditional harvest of cochineal scales on Tenerife, Canary Islands (L and LC), the dried, cleaned insects (C) for sale (RC) and with one added to a glass of water, releasing the red dye (R). In addition, several species of Dactylopius are used as biological control agents against invasive species of Opuntia cactus.Ī cochineal farm on Tenerife, Canary Islands (L), colonies of cochineal scales on a cactus pad (LC), closeup of cochineal scales (C and RC) and desiccated females without the protective white wax (R). Cochineal scales ( Dactylopius spp.), which grow only on cactus, produce red dyes for coloring foods and dyeing fabrics, several genera of lac scales produce shellac, and there are other species that produce other less common materials. There are, however, a few types of scale insects which are economically valuable and are “farmed” for the substances they produce. Sooty mold is a black-colored fungus when it coats the top side of leaves, that interferes with photosynthesis and makes the plants unattractive and yellow. Many also excrete sticky honeydew which supports the growth of sooty mold. They feed by sucking plant sap through their long, needle-like mouthparts (six to eight times longer than the insect itself!). Most species are restricted to particular host plants or plant groups, and some are serious crop pests. Scale insects feed on a wide range of host plants and are common pests of many indoor and outdoor herbaceous ornamental plants as well as many trees and shrubs. The substance is a food source for this black sooty mold fungus on these gardenia leaves. Yellowish coffee green scales produce a sweet, sticky liquid called honeydew. When they molt to the next instar almost all female scales lose their legs and are sedentary as adults only a few species have the ability to move after the crawler stage. Usually smaller than a pinhead, in general they move around searching for a favorable spot to settle down to feed and begin producing their distinctive scale coverings but in some species they are moved by wind to settle on other plants. Females lay eggs under their bodies which hatch into the first instars, called crawlers, which do have legs and are mobile.Ĭottony cushion scales infesting a citrus tree. Some species are hemaphroditic while others reproduce by parthenogenesis. The seldom seen male scale looks somewhat like a tiny gnat but doesn’t have mouthparts and cannot feed. This covering which protects the insect underneath it may be a flattened oval, dome-shaped, oyster shell-shaped, resemble small mussels, or have a fluffy coating.Ī gnat-like male scale ( Dactylopius sp.).įemale scales, usually immobile, are wingless and often with no visible legs or antennae and don’t even look like an animal. These small insects vary a lot in size (from 1/16 to 3/8 inch across) and appearance but all grow beneath a wax covering that resembles an individual reptile or fish scale, hence the common name. Scale insects are a large and diverse group (about 8,000 described species) in the superfamily Coccoidea of the order Hemiptera, closely related to aphids and whiteflies, but they look quite different from your typical insect (the mealybugs are part of this superfamily, too, but are not included in this article). Various stages of soft scales attended by ants.
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