Soft scales

Definition

A common name for scale insects in the family Coccidae (Hemiptera: Sternorrhyncha: Coccoidea), characterized by a soft, often convex or waxy covering that is not separable from the body, and by the retention of legs and antennae in most adult females. Unlike armored scales (Diaspididae), soft scales lack a hard, separable protective test and typically excrete copious honeydew, often establishing mutualisms with ants and fostering sooty mold growth.

Etymology

From the soft, flexible, often waxy or cottony covering secreted by these insects, contrasting with the rigid, separable armor of armored scales.

Example

The brown soft scale Coccus hesperidum and the cottony cushion scale Icerya purchata are economically important pests of citrus and ornamental plants; their honeydew excretion promotes sooty mold that reduces photosynthesis.

Synonyms

• Coccidae (family name)
• Wax scales
• tortoise scales

Related Terms

• Armored scales
• Mealybugs
• scale insects
• Sternorrhyncha
• honeydew
• Sooty mold
• test
• Diaspididae

Usage Notes

The term is applied to the family Coccidae in a broad sense, though some taxonomists restrict 'soft scales' to certain subfamilies or exclude groups now placed in separate families (e.g., Kerriidae, Lecanodiaspididae). Adult females are sessile and often morphologically reduced; males are typically winged and short-lived. The distinction from 'armored scales' (Diaspididae) is ecologically and morphologically significant but can be blurred in field identification when waxy secretions are sparse.