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KAC Citrus Entomology
University of California
KAC Citrus Entomology

Cottony Cushion Scale

Vedalia beetle adult
Vedalia beetle adult
Cottony cushion scale lifecycle

Basic Information

Life Cycle: Cottony cushion scale, Icerya purchasi, starts its life cycle as a crawler that emerged from the white sac of the female scale.  The crawler settles on a leaf or twig and molts twice for a total of 3 nymphal instars.  The third instar moves to the heavy twigs and molts into an adult female.  The females can reproduce without mating.  The entire lifespan requires about 12 weeks to complete.  For more information on the lifecycle see ANR publication 8051 Cottony Cushion Scale and its Natural Enemy, the Vedalia Beetle.

Host List: Cottony cushion scale is found primarily on citrus and a few ornamental hosts such as Pittosporum and Nandina.

Damage: If densities of cottony cushion scale become heavy, sooty mold will build up on the honey dew they produce, twigs will die, and yield will be reduced.

Distribution: Originally from Australia, this pest is found through California citrus. 

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