scale insect

scale insect (plural scale insects)

1. Any of the small parasitic insects of the superfamily Coccoidea, that live on plants and sap nutrients from them.
   • 2005, Hans G. Schabel, Forest Entomology in East Africa: Forest Insects of Tanzania‎, page 93:

     Male scale insects are mostly haploid, undergo an unusual metamorphosis, and feed only in the first two instars.

   • 2008, Nathaniel B. Hardy, Systematic Studies of Scale Insects (Hemiptera: Coccoidea), page 1,

     Scale insects (Hemiptera: Coccoidea) are a diverse group (>7,300 species) of plant parasites that are closely related to aphids. Several species of scale insects are very serious pests of agriculture, whereas others are cultivated for dyes, lacquer, or for use in biological control of invasive plants. All scale insect species in which males occur are sexually dimorphic.

   • 2011, Ross Piper, Pests: A Guide to the World's Most Maligned, Yet Misunderstood Creatures‎, page 149:

     Secondly, the sheer volume of sap a scale insect imbibes would quickly inflate it to bursting, but an efficient fluid balance mechanism—the insect equivalent of vertebrate kidneys—quickly extracts the surplus fluid from the sap and excretes it as honeydew, the sugary water that all sap-feeding insects excrete in copious quantities. In heavy infestations of scale insects, the honeydew may be produced in sufficient quantities to coat the leaves and other parts of the plant, impairing the plant's ability to photosynthesize and encouraging the growth of fungi.

• scale (in combination, in vernacular species names)