Juniper Pests

Juniper is a hardy plant that can handle diverse conditions, but pests can be trouble for this low-maintenance evergreen. Various bugs can harm the vibrant green foliage and woody branches, but learning to spot the signs of bug damage allows you to minimize an infestation and help the shrub recover. Learn more about the pests most likely to harm juniper shrubs and how to protect your plants from damage. 

Common Juniper Pests

Bagworm

Bagworms are a type of caterpillar that prefers evergreen plants like junipers. These pests eat the foliage, stunting growth in a minor infestation. A large infestation can strip the juniper of needles and kill the plant.

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Photo by Steve Rainwater, cropped, Flickr, Copyright CC BY-SA 2.0 DEED

Treating Bagworm on Juniper

Bagworm larvae emerge in the spring, and the plants should be treated at the first sighting of these pests. Spray the plant with an insecticide to kill the eggs, larvae, and adult insects. Depending on rainfall and other factors, it may take several applications of insecticide to kill the bagworm population.

Preventing Bagworm on Juniper

If you have had previous trouble with this pest, bagworm prevention is in order. Instead of waiting for confirmation that bagworms are in your juniper, spray the plant with an insecticide to kill any eggs or larvae that have not yet emerged.

Spruce Spider Mites

Spruce spider mites are tiny, sap-sucking pests. The actual bugs are hard to see with the naked eye, but their damage is apparent. The foliage develops tiny yellow specks after spruce spider mites feed on a juniper. Needles will eventually turn brown and fall off. Aside from the damage, fine webbing tangled on the branches indicates spruce spider mites. These pests stunt the growth of a juniper plant. Spruce spider mites can kill a plant, but it takes several years of infestation without intervention.

Treating Spruce Spider Mites on Juniper

Ladybugs are natural predators of spruce spider mites, so encourage these beneficial bugs and do not do anything to discourage ladybugs from living and thriving in your landscape. Use an insecticidal soap in a heavy infestation, but be mindful that this may negatively impact helpful insects, like ladybugs.

Preventing Spruce Spider Mites on Juniper

Prevent spruce spider mites by encouraging natural predators, like ladybugs. Preemptively spray the shrub with an insecticidal soap if you have struggled with this pest in the past.

Juniper Scale

Scale are small pests that suck sap from a plant, effectively depriving the shrub of nutrients. Juniper scales target the branches and appear as clusters or bumps on the underside. Infested plants will develop yellow foliage and stunted growth. Juniper scale can kill a plant after several growing seasons. 

chilocorus-bipustulatus-larvae-on-juniperus-communis-with-its-food-scale-insects-probably-carulaspis-juniperi-.jpg

Photo by Gilles San Martin, unedited, Flickr, Copyright CC BY-SA 2.0 DEED

Treating Scale on Juniper

Take on a heavy infestation of juniper scale by applying an insecticide. It may take several applications to kill adults, larvae, and eggs. Be patient and continue to monitor the plant.

Preventing Scale on Juniper

Prevent juniper scales by spraying the plant with horticultural oil in the late winter or early spring. A well-timed dose of horticultural oil will kill the female bugs before they lay eggs, effectively killing a future colony. Spray the juniper shrub every few weeks during the early spring to ensure any unseen pests or eggs are destroyed.

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Author Alison Cotsonas - Published 12-22-2023