Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

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Citrus snow scale (105)

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Photo 1. Female citrus snow scale, Unaspis citri. The female is very different from the male; it is oval, brown-black and 2 mm long, whereas the male is 1 mm, and white.

Diagram. Life-cycle of an armoured scale.

Summary

• Worldwide distribution. Mostly, citrus, but the Pacific banana is a host. An important pest.
• The scale has tube-like mouthparts, sucking sap from stems. Heavy infestations cause leaf fall and dieback.
• Eggs hatch and “crawlers” walk or spread by wind, settle, feed and produce the protective armour, oyster-shaped in females, white and straight in males. Males become fly-like, without mouthparts, mate and die.
• Natural enemies: ladybird beetles and parasitoid wasps.
• Cultural control: scale-free nursery stock; Gliricidia windbreaks to protect from spread of "crawlers"; adequate nutrition.
• Chemical control: use lime sulphur or wettable sulphur, leaving 30 days if also spraying oils (READ INSTRUCTIONS); alternatively, spot-spray infestations with horticultural oil, white oil, or soap solution (see Fact Sheet no. 56); avoid malathion and synthetic pyrethroids - they will kill natural enemies.

Common Name

Citrus snow scale, white louse scale

Scientific Name

Unaspis citri

This mini fact sheet is a part of the app Pacific Pests, Pathogens & Weeds

The mobile application is available from the Google Play Store and Apple iTunes.