Carulaspis juniperi (Bouche)
The juniper scale, native to Europe, is now distributed throughout the United States. This key pest is known to attack junipers, Juniperus spp.; cypresses, Cupressus spp.; falsecypress, Chamaecyparis ; and incense cedar, Calocedrus decurrens . Ornamental plantings of juniper most commonly infested include eastern redcedar, J. virginiana ; Irish juniper, J. hibernica ; Savin juniper, J. sabina ; and Chinese juniper, J. chinensis ‘Pfitzeriana’. This armored scale insect occasionally becomes a problem in landscapes and nurseries.
Eggs hatch into yellow first instar nymphs called crawlers. The female’s waxy cover is parchmentlike, white with a circular, slightly convex, yellow center that is about 1.5 mm in diameter (Fig. 1). The white waxy cover of the male is smaller and oblong shaped. Mature males emerge as winged insects that resemble tiny wasps walking on an infested twig.
Figure 1. Close-up of female juniper scales.
This species overwinters as mature fertilized females. In spring they lay an average of 40 eggs around mid-May that hatch into crawlers in 10-14 days. Crawlers seek a new feeding site on the host plant. Females go through three growth stages prior to reaching maturity while the male goes through five. In late summer males emerge, mate with females, and then die. There is one generation each year in Pennsylvania.
The first indication of plant injury caused by this scale insect is the loss of normal lustrous color. As an infestation becomes more severe, foliage on individual branches will look chlorotic or yellow and may eventually die. Entire plants are known to die as the result of severe infestations.
Apply registered insecticides according to label directions from late May through June to reduce populations of the crawler stage of this pest. Dustywing larvae and adults, predators in the insect family Coniopterygidae, feed on eggs and other life stages of this scale insect. Lady beetle larvae and adults are often associated with infestations of this armored scale. Four species of wasp parasitoids are known to attack this pest.
Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.
Authored by: Gregory A. Hoover, Sr. Extension Associate
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