Quadraspidiotus perniciosus

Quadraspidiotus perniciosus

San Jose Scale
Binomial:	Quadraspidiotus perniciosus
Order:	Hemiptera
Metamorphosis:	Simple
Damaging stages:	Nymphs
Vulnerable stages:	Crawler

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

Control

• Trapping: Electrical tape (sticky side out) around a branch can detect the presence of crawlers.
• Physical removal: Prune out infested branches
• Organic pesticides: Horticultural Oil (dormant spray), Neem Oil
• Predators and parasites: Wasps including Encarsia perniciosi and Aphytis spp.

References

• Virginia Tech
• West Virginia University
• Ohio State University