Red scale is the most widespread pest of citrus in New South Wales.

Description

• Females have four, and males five, development stages.
• All stages are sessile (non-free-moving) except the early part of the first stage (crawlers) and adult males (winged).
• The scale cover of the female is circular (about 2 mm diameter), whereas that of the male is elongated.
• The colour of the scale cover changes from white in the first stage to reddish brown in later stages.
• Depending on temperature, red scale has two to five generations per year in NSW.

Damage

• It infests leaves, fruits, twigs and limbs of all varieties of citrus.

Monitoring

• Check five fruits per tree during October–March.

Natural enemies

• Aphytis wasp
• Ladybirds
• Chilocorus
• Predatory mites

Control measures

• Take appropriate actions if 10% or more of fruits of early varieties are infested, or 15–20% or more of later varieties are infested. Appropriate actions include releasing parasitic wasps and the application of petroleum spray oil.
• When choosing the latter option, time the spray when young scales are predominant.

More information

• Pest management guidelines (www.ipm.ucdavis.edu)
• Information on Aphytis biological control (www.bugsforbugs.com.au)