Juniper Scale Fact Sheet
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Juniper Scale, Carulaspis juniperi (Bouche), an introduced pest of
European origin, is an occasional problem in the western Pennsylvania
landscape. It feeds on the stems or leaves of the host plant, with
moderate infestations resulting in unsightly brown patches. The insect
will often go unnoticed until the plant declines or dies if
the infection is severe.
Plants Attacked
The ornamental junipers most commonly attacked are redcedars, Juniperus
virginiana, Irish juniper, J. hibernica, Savin juniper, J. sabina and Pfitzer juniper, J. chinensis 'Pfitzeriana'.
Juniper scale will also attack cypresses, Cupressus ssp., falsecypress,
Chamaecyparis ssp., and incense cedar, Calocedrus decurrens.
Insect Identification
The adult female scale is 1/16" - 1/20" in diameter and
white colored with a central yellow spot, and resembles a miniature
fried egg. Male scales are smaller with a more elongated appearance
and a yellow spot on one end. Newly hatched crawlers are bright yellow,
but soon fade to a tan color before forming their white waxy covering.
They are most readily found on the underside of the foliage and may
also be revealed by tapping an infested twig over a piece of white
paper.
 |
 |
| Juniper scale on Chamaecyparis |
Juniper scale crawlers and adults |
Life History
| Winter |
The female, filled with eggs, over-winters on the foliage. |
| Spring |
The female matures and then dies soon after laying up to 40
eggs (mid-May). |
| Summer |
The crawlers emerge from underneath the female scale (throughout
June) and settle at a new feeding site on the same host plant.
They can also be blown onto other plants or spread by birds. In
late summer, (early July through mid-August) the male seeks out
the female, they mate and the male dies soon after. |
| Fall |
The female continues to grow until late fall, at which time she is nearly
fully developed and ready to over-winter. There is one generation
of juniper scale per year in Pennsylvania. |
Damage Symptoms
 |
| Normal foliage (top) scale infested
foliage (bottom) |
Light infestations result in foliage that is off
color and less lustrous
looking. If uncontrolled,
the foliage turns brown, and branch dieback
occurs. In the extreme case, the plant dies.
Management Options
| Biological |
The larval and adult stages of dustywings and lady beetles are
common predators of juniper scale and several species of parasitic
wasps help control this pest. . If beneficial predators are present,
the use of "predator friendly" insecticides such as
insecticidal soap or horticultural oils should be used, and pest
populations closely monitored. |
| Mechanical |
The removal of heavily infested foliage will reduce the population
and help manage the infestation. |
| Chemical |
Dormant horticultural oil applied in early spring can be
used to suppress an outbreak of scale. It is not as effective
in areas where scale is clustered together. Contact insecticides
may be used during the growing season to kill the newly hatched
nymphs (crawlers) but will not kill the adult scale.
Control
for Juniper Scale |
Related Species
A closely related species, Carulaspis minima attacks arborvitae,
Thuja sp., spruce, Picea sp. and probably all the species attacked
by the juniper scale.
Download Printable Fact Sheet
Authored by:
Katherine Mazzey, Penn State Extension Program Assistant
Michael Masiuk, Extension Agent, Penn State
University - Allegheny County
Sources:
Hoover, G.A. (2000).Woody Ornamental Insect,
Mite, and Disease Management. Penn
State College of Agricultural Sciences. pp. 36.
http://woodypestguide.cas.psu.edu/
Hoover, G.A. (2001).Juniper Scale. Entomological
Notes, Department of Entomology,
Penn State University.
http://www.ento.psu.edu/extension/factsheets/juniperscale.htm
Johnson, W.T. & Lyon, H.H. (1976).Insects That
Feed On Trees And Shrubs, pp106.
Comstock Publishing Associates. Cornell University Press.
Klass C. (1986). Juniper Scale. Cornell University.
Department of Entomology.
http://www.cce.cornell.edu/factsheets/pest-fact-sheets/old/wo.pst.junipers.html
Townsend, L. (1996). Juniper Scale. University of
Kentucky Entomology.
http://www.uky.edu/Agriculture/Entomology/entfacts/trees/ef429.htm
Virginia Polytechnic Institute & State University
(1996). Virginia Cooperative Extension.
Juniper Scale. http://www.ext.vt.edu/departments/entomology/factsheets/junscale.html
