Juniper Borers
Trachykele blondeli (Marsuel)
Callidium spp.
Atimia spp.
Chrysobothris spp.
Styloxus bicolor (Champlian and Knull)

Hosts:  Junipers and Arizona cypress

Symptoms/Signs:  Exit holes.

Effects:  Several roundheaded and flatheaded wood borers are aggressive pests in drought-stressed junipers and cypress. Damage can be extensive before symptoms are apparent. Usually a large portion of the tree or the entire tree dies before the insects’ exit holes are noticed.

Biology:  Callidium spp. larvae bore beneath the bark making very wide tracks that distinctively score the outer sapwood much like a router. Older larvae excavate oval tunnels deep in the wood and overwinter. Adults emerge throughout the warm months of the year. There is one generation per year. Adult beetles are rather short-horned for cerambycids and dark blue or black. These roundheaded borers leave an oval or rectangular exit hole.
Atimia spp. are small roundheaded borers about 6.5 mm long and generally have a 1-year life cycle. These longhorned beetles attack thin bark portions of seriously weakened and dead juniper and cypress.

Trachykele blondeli, the western cedar borer, is 11 to 17 mm long and attacks juniper and Arizona cypress. Females lay eggs under bark scales and branches of living trees. Flatheaded larvae bore from the branches into the main bole. They feed primarily in the heartwood for several years. Adults emerge in the spring, leaving oval or rectangular exit holes.

Chrysobothris spp. are flatheaded borers of junipers and Arizona cypress. They are medium-sized beetles about 11.5 mm long. Larvae bore into the bark and outer wood of weakened trees.

The juniper twig pruner, Styloxus bicolor, is a small roundheaded borer that mines the small branches and causes twig dieback during dry periods.

Similar Insects and Diseases:  See cedar bark beetles.

References:  9, 23