Unaspis citri

Definition

A species of armored scale insect (Hemiptera: Diaspididae) that infests citrus and related Rutaceae, forming dense, white, waxy coverings on bark, leaves, and fruit. The female secretes a protective, snow-like test (covering) that obscures the underlying body, while males produce smaller, elongated coverings. Heavy infestations cause chlorosis, dieback, and reduced fruit quality through direct feeding damage and honeydew accumulation that promotes sooty mold. Native to Asia, it is a significant pest of commercial citrus worldwide, particularly in subtropical and tropical regions.

Etymology

Unaspis from Greek 'una' (one) + 'aspis' (shield), referring to the single, unified protective covering; citri from Latin 'citrus,' the host plant genus.

Example

In Florida groves, Unaspis citri populations build up on the trunk and scaffold branches of mature grapefruit trees, producing conspicuous white encrustations that can completely mask the bark texture and require systemic insecticide or biological control using parasitoid wasps such as Aphytis lingnanensis.

Synonyms

• citrus snow scale
• orange chionaspis
• orange snow scale
• white louse scale
• white snow scale

Related Terms

• Diaspididae
• armored scale
• test
• Coccoidea
• citrus pest
• Biological control
• Integrated Pest Management

Usage Notes

The common name 'citrus snow scale' refers to the white, powdery appearance of heavy infestations, not to cold tolerance. The species is distinguished from other Unaspis by host association and test morphology; accurate identification requires slide-mounting and examination of pygidial ducts. The name 'white louse scale' is archaic and may cause confusion with mealybugs (Pseudococcidae).