Magnolia scale is our largest soft scale insect, reaching ½ inch in length. This scale spends the winter on one-to-two-year-old twigs as tiny, dark-colored nymphs. In the spring, the scales begin to feed, mature, and change color. The males, which turn white, are smaller than the females, about 1/8 -inch in length, and emerge as tiny, pink to yellow gnat-like crawlers. The females turn white to brownish-purple in color and continue to expand through July. Magnolia scale eggs hatch internally, and the crawlers are born alive. Crawler emergence occurs in the early fall. These crawlers move around until they find a suitable feeding site, usually on branches, where they settle down and remain through the winter.
Control of scale insects varies with the species. A waxy covering protects most adult armored scales, therefore control measures must be aimed at the unprotected crawlers or applied during the over wintering stage.
Dormant oils are effective on the overwintering stage of most species, but need to be applied in early spring before leaves appear. They are less effective on armored scale species.
Insecticidal soaps can be effective against the crawler stage but usually have no effect on the adult scale.
Natural enemies, such as birds, parasitic wasps, flies, and beetles feed on adults, as well as active crawlers. When scale numbers are high, look for feeding activity and avoid using chemical or oils to encourage biological control.
Scale insects are very vulnerable in the crawler stage when the young are looking for a place to feed. Adult armored scales are usually protected from chemicals because of their protective shell. Registered sprays applied before the crawlers are present will have little effect on population control. Timing of application is critical and will vary with species.
SCALE TIME TO TREAT (crawlers)
Treat Magnolia scale in mid-to-late September with acephate or malathion
Refer to the Illinois Urban Pest Management Handbook (University of Illinois Cooperative Extension Service) for a complete listing of chemical recommendations. Use pesticides safely and wisely; read and follow label directions.
The pesticide information presented in this publication is current with federal and state regulations. The user is responsible for determining that the intended use is consistent with the label of the product being used. The information given here is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement made by The Morton Arboretum.
- Ann Magnolia 33%
Botanical Name: Magnolia 'Ann'Common Name: Ann Magnolia Form Bud Flower Click on image to enlarge.Height: 8-10'Spread: 8-10'Form: Upright, shrubbyFlowering...
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Botanical Name: Magnolia denudataCommon Name: Yulan Magnolia Form Flower Bark Height: 30-40'Spread: 25-30'Form: Broad pyramidalFlowering Period: Late AprilZone: ...
- Elizabeth Magnolia 32%
Botanical Name: Magnolia 'Elizabeth'Common Name: Elizabeth Magnolia Form Flower Bark Height: 30-50'Spread: 20-35'Form: Upright, pyramidalFlowering Period: Mid-MayZone: ...
- White-barked Magnolia 32%
Common Name: White-barked Magnolia Botanical Name: Magnolia hypoleuca Form Flower Bark Height: 25-35'Sread: 20-25'Form: Broadly openFlowering Period: May-JuneZone: ...
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Botanical Name: Magnolia acuminata Common Name: Cucumbertree, Cucumber Magnolia Updated 10/2012 Click on an image to enlarge form fruits fall color Height: 50-70' Spread: 50-60' Habit/Form: Pyramidal to rounded Growth...