Juniper Flatheaded Borers are wood-boring beetles that attack stressed or weakened juniper plants. Their larvae tunnel through wood, disrupting the plant’s vascular system and causing significant damage.
Juniper flatheaded borers (primarily Chrysobothris sylvania or Chrysobothris texana) are highly destructive wood-boring beetles that pose a severe threat to the structural integrity of junipers, cypresses, and arborvitae. As members of the Buprestidae family, they are known as “metallic wood-borers” due to the iridescent, jewel-like sheen of the adult beetles. In the arid landscapes of Tucson, these borers are “stress-seekers,” using infrared sensors to locate trees weakened by drought, transplant shock, or recent construction damage.
The damage is caused by the larvae, which are cream-colored, legless grubs with a distinctively widened, flattened segment behind the head—hence the name “flatheaded.” Upon hatching from eggs laid in bark crevices, the larvae bore into the cambium layer, the vital tissue responsible for transporting water and nutrients. They excavate winding, “S-shaped” galleries packed with fine, sawdust-like excrement called frass. As these galleries expand, they effectively “girdle” the branch or trunk, cutting off the tree’s life support system.
For Pestipedia readers, early detection is difficult because the larvae remain hidden. Look for “D-shaped” exit holes in the bark, oozing sap (pitch), or “flagging” where large sections of the canopy suddenly turn brown. Because the larvae are protected deep within the wood, management focuses heavily on prevention: maintaining tree vigor through deep watering during dry months and avoiding mechanical wounds that leak the “stress scents” that attract egg-laying females.
Taxonomy
- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Insecta
- Order: Coleoptera
- Family: Buprestidae
Identification
Larvae are flattened and pale, while adults are metallic beetles.
Habitat and Distribution
Common in dry climates and stressed landscapes.
Life Cycle
Eggs are laid on bark, larvae tunnel through wood.
Damage and Impact
Tunneling disrupts nutrient flow, causing dieback and potential death.
Signs of Infestation
D-shaped exit holes and dieback are indicators.
Prevention and Control
Maintaining plant health reduces susceptibility.