Hemiptera: Coccoidea


Scales are distinguished by a cottony or waxy covering that protects the insect body. Mature female scales are wingless while males have a pair of delicate wings. The size of scale insects ranges from 1/8 to ½ inch. Scale insects are generally divided into two groups: Soft scales produce a soft, cottony, or powdery layer over themselves that is connected to the body; and Armored scales have a hard waxy cover above their body that is not attached to the body of the insect.

Life Cycle

Scale insects have three life stages: egg, nymph, and adult. Females lay eggs either entirely under their protective covers or underneath an additional secretion of cottony wax. Mature females die after laying eggs. When eggs hatch, the crawlers actively wander around to find a place to feed. Once they choose a suitable location, they insert their piercing-sucking mouthparts into the plant and begin to feed on the sap. After feeding begins, they settle and quickly develop their waxy shell. In most species, nymphs and adult females remain in the same location for the rest of their lives while winged males fly to new females for mating. Generally, soft-scale insects have one generation per year, while armored scales have several generations per year.

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Scale insects feed sap from plants through piercing-sucking mouthparts. Sap feeding may cause leaf yellowing, premature leaf drop, stunting of growth, or twig dieback when infestations are heavy. Soft-scale insects excrete a sweet, sticky substance onto leaves called honeydew. Honeydew attracts insect scavengers like ants and may encourage sooty mold. Sooty mold is a fungus disease that grows on plants and covers the leaves resulting in less photosynthesis to provide enough energy for plants.



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