Horticulture/Quadraspidiotus perniciosus

San Jose scale is a pest of both orchards and ornamental plants. The insect is originally from China, but introduced in North America in the late 1900s as an invasive species.

Description
Circular hard scales, generally in great numbers. Adult males are winged, females remain under the scale.

Symptoms and Signs
Severe infestations can kill the host plant if not treated.

Host plants

 * ../Asclepias/
 * ../Buxus/
 * ../Celtis/
 * ../Cornus/
 * ../Crataegus/
 * ../Cydonia/
 * ../Fagus/
 * ../Gleditsia/
 * ../Juglans/
 * ../Ligustrum/
 * ../Lonicera/
 * ../Maclura/
 * ../Malus/
 * ../Morus/ (Mulberry)
 * ../Pachysandra/
 * ../Photinia/
 * ../Prunus/
 * ../Ribes/
 * ../Robinia/
 * ../Rosa/
 * ../Rhamnus/
 * ../Sassafras/
 * ../Sorbus/
 * ../Syringa/ (Lilac)
 * ../Thuja/ (Arborvitae)
 * ../Tilia/
 * ../Viburnum/