San Jose Scale

Pest: San Jose scale (Diaspidiotus perniciosus)

Pest Type: Insect Pest

San_Jose_Scale_Scales_enlarged(PSF)

Major Identifying Features: Scale insects feed by sucking plant juices and some inject toxic salvia into plants, scales look different than other insects, females are circular to oval, wingless, and lack separate head or other recognizable body parts, males are tiny, delicate, white to yellow with one pair of wings and antennae, females can reproduce without mating

Life Cycle: Complete metamorphosis, 4 stages (egg, larva, pupa, adult), eggs are produced beneath the body or cover of the female, females have a smooth, yellow body beneath the gray round cover with indentations, nymphs walk along branches or spread with the wind, nymphs are yellow to orange and the size of a period, once they start feeding, they remain immobile for the rest of their lives, overwinter in the black cap which develops around the white cap, a waxy covering, 2-5 generations per year

Pest Rating: Minor to moderate

Management Rating: Easy to moderate

Host/Season/Outbreak Information: Warm temperatures usually favour scale outbreaks and honeydew protecting ants are around, acacia, aspen, cottonwood, fruit trees, maple, mulberry, poplar, pyracantha, walnut, willow, roses

Damage Information: When numerous, some species can weaken a plant and cause it to grow slowly, infested plants appear water-stressed, leaves can turn yellow, and may drop prematurely, plants infested by soft scales and certain other species become sticky from honeydew and may blacken due to sooty mold growth, serious on nut trees and stone fruits

Management Options: Prevention and monitoring with sticky traps, controlling dust, cultural control with appropriate plant selection, biological control with predatory bugs, beetles, and lacewings (Chilocorus, Hyperaspis, Rhyzobius), parasitic wasps, chemical applications with horticultural oils in spring or summer

Sources:

Pests of Landscape Trees and Shrubs (Book)

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