Pest identification
What's eating my holmstrup arborvitae?
Deer
Signs: Foliage stripped from exposed branches; repeated browsing prevents the columnar form from developing
Control: Deer repellent applied every 2–3 weeks; tree tubes on young plants; fencing in high-pressure areas
Bagworm (Thyridopteryx ephemeraeformis)
Signs: Camouflaged bags visible by mid-summer; defoliated branch stubs remain after larvae pupate
Control: Hand removal of bags in late winter; Bt or spinosad spray in late June
Spider mites (Tetranychus spp.)
Signs: Bronze, dusty-looking foliage in summer; shake a branch over white paper to see moving mites
Control: Horticultural oil or insecticidal soap spray; ensure adequate irrigation to reduce plant stress
Keep holmstrup arborvitae pest-free
Healthy plants resist pests best. Get the basics right:
Holmstrup Arborvitae pests — FAQ
What is eating my holmstrup arborvitae?
Holmstrup Arborvitae faces the same core threats as other Thuja occidentalis cultivars. Deer browsing is the most disfiguring pest in suburban and rural settings. Bagworms can fully defoliate branches if undetected. Spider mites and leafminers cause tip dieback. Monitor throughout summer and act early.
How do I get rid of deer on holmstrup arborvitae?
Foliage stripped from exposed branches; repeated browsing prevents the columnar form from developing Deer repellent applied every 2–3 weeks; tree tubes on young plants; fencing in high-pressure areas
How do I get rid of bagworm (thyridopteryx ephemeraeformis) on holmstrup arborvitae?
Camouflaged bags visible by mid-summer; defoliated branch stubs remain after larvae pupate Hand removal of bags in late winter; Bt or spinosad spray in late June
How do I get rid of spider mites (tetranychus spp.) on holmstrup arborvitae?
Bronze, dusty-looking foliage in summer; shake a branch over white paper to see moving mites Horticultural oil or insecticidal soap spray; ensure adequate irrigation to reduce plant stress