California red scale

Definition

A regional common name for the armored scale insect Aonidiella aurantii (Hemiptera: Diaspididae), a serious pest of citrus and other fruit crops. The name refers specifically to populations in the United States, particularly California, where the species was introduced between 1868 and 1875 on Australian planting material. The insect produces a circular, reddish-brown protective cover (test) and feeds on phloem sap, causing fruit blemish, leaf yellowing, twig dieback, and tree decline. It is distinguished from yellow scale (Aonidiella citrina), a congener with similar biology but paler coloration and slightly different host preferences.

Etymology

California for the U.S. state where it was first detected and became economically significant; red for the color of the adult female's protective test; scale from the characteristic armored covering secreted by female Diaspididae.

Example

Integrated pest management programs for California red scale in San Joaquin Valley citrus rely on augmentative releases of the parasitoid wasp Aphytis melinus, timed to scale crawler emergence detected by double-sided sticky tape traps wrapped around scaffold limbs.

Synonyms

• red scale
• Aonidiella aurantii

Related Terms

• armored scale
• Diaspididae
• yellow scale
• Crawler
• test
• phloem feeder
• Integrated Pest Management
• Biological control
• citrus pest
• San Jose scale

Usage Notes

The name "California red scale" is used primarily in North America; elsewhere the species is simply called "red scale." Specialists distinguish it from "yellow scale" (Aonidiella citrina) by cover color, though microscopic examination of morphological characters is required for definitive identification. The term is sometimes misapplied to other reddish armored scales on citrus. In IPM contexts, "CRS" is common shorthand.