Juniper Soft Scales are sap-feeding insects that attach themselves to stems and foliage of juniper plants. These pests are particularly problematic because they produce large amounts of honeydew, a sticky substance that promotes the growth of sooty mold. Over time, infestations can weaken plants and reduce their overall health and appearance.
Juniper soft scales (primarily Parthenolecanium Fletcheri, also known as the Fletcher Scale) are specialized sap-sucking insects that can be a major nuisance for ornamental junipers, arborvitae, and yews. Unlike “armored” scales that have a separate, hard waxy shield, soft scales produce a protective body wall that is part of the insect itself. In the Tucson area, these pests are often overlooked because their hemispherical, glossy-brown bodies mimic the color and shape of juniper buds or small bark bumps.
The damage caused by juniper soft scales is twofold. First, they use piercing-sucking mouthparts to drain the plant’s essential fluids, leading to a general loss of vigor, needle yellowing, and eventual branch dieback. Second, as they feed, they excrete massive amounts of honeydew. This sticky residue covers the foliage and attracts “nuisance ants” that protect the scales from ladybugs and other predators. The honeydew also serves as a substrate for sooty mold, a black fungus that can coat entire sections of the tree, blocking photosynthesis and ruining its aesthetic appeal.
For Pestipedia readers, the “crawler” stage—the mobile, newly hatched nymphs—is the most vulnerable time for management. This typically occurs in late spring. Because the adult females are protected by their toughened body shells, contact sprays are often ineffective against them. Management focuses on horticultural oils or insecticidal soaps applied during the crawler window, or systemic treatments that the plant absorbs into its vascular system.
Taxonomy
- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Insecta
- Order: Hemiptera
- Family: Coccidae
Identification
Soft scales appear as small, rounded bumps on plant surfaces. They may be brown, tan, or yellow and often blend in with the plant.
Habitat and Distribution
Common in landscapes and nurseries where junipers are grown.
Life Cycle
Eggs hatch into crawlers that settle and feed.
Damage and Impact
Feeding causes yellowing, reduced growth, and mold development.
Signs of Infestation
Sticky residue and black mold are key indicators.
Prevention and Control
Oils and soaps help control populations.