Pest profile

Cypress Bark Beetles

Phloeosinus species · Coleoptera: Curculionidae[3]

Cedar and cypress bark beetles are small native bark beetles that attack junipers, Arizona cypress, Leyland cypress and other cypresses, girdling branches of stressed trees so foliage browns and dies.[1][2]

Cedar bark beetle, a tiny brown Phloeosinus beetle
Cedar bark beetle, a tiny brown Phloeosinus beetle. (c) Elliott Gordon, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are about 1/8 inch long, black to reddish brown; larvae are legless white grubs with a brown head.[1]
  • Signs include discolored or dead branch tips and twigs and boring dust (frass) on the bark.[1]

Where it lives

Utah State reports them on Utah and Rocky Mountain juniper, eastern red cedar and cypresses, and Arizona Extension on ornamental Arizona and Leyland cypress.[1][2]

US map: public records from 21 states since 1990 (GBIF).

Biology and life cycle

They overwinter as larvae under the bark and usually have one generation a year, sometimes two.[1]

Adults can attack from spring to fall depending on location, mostly mid to late summer in Utah.[1]

Damage and signs

  • Healthy, vigorous trees can usually withstand substantial beetle pressure, but many trees die during extended drought.[1][2]
  • Both larvae and adults cause damage, and girdling can kill branches or whole trees.[1]

Health risk

None to people or pets.[1][2]

Control

Prevention

Keep trees vigorous with deep, infrequent irrigation during drought, and don't overwater.[1][2]

Sanitation

Prune dead or dying branches in winter and remove them from the site.[1]

Pesticides

Where beetles are active, susceptible trees can be protected with a labeled bark spray (carbamate or pyrethroid) on the main stem and branches.[1]

Common questions

Why are branches on my Arizona cypress dying?
Cypress bark beetles girdling branches of drought-stressed trees are a common cause.[1][2]
How do I protect cypress trees from bark beetles?
Water deeply and infrequently during drought; healthy trees can usually withstand the beetles.[1][2]
When should infested branches be removed?
Prune dead or dying material in winter and remove it from the site.[1]

Sources

  1. Utah State University Extension, “Cedar/Cypress Bark Beetles (Ornamental Pest Guide).” extension.usu.edu/planthealth/ipm/ornamental-pest-guide/arthopods/bark-beetles/cedar-cypress-bark-beetles.php (accessed 2026-10-15)
  2. University of Arizona Cooperative Extension, “Cypress Bark Beetles (AZ1316, December 2011).” extension.arizona.edu/publication/cypress-bark-beetles (accessed 2026-10-15)
  3. iNaturalist, “Phloeosinus taxon page (order and family).” www.inaturalist.org/taxa/178452 (accessed 2026-10-06)

Updated 2026-10-15. Built from sourced records. Spot an error? Tell us.