Flatheaded Borers on a Juniper

Description

• Flatheaded borers are common pests of a wide variety of softwood and hardwood trees. Adult flatheaded beetles are metallic, blue, green, black or copper colored with flat, elongated to oval bodies and grooves on their wings. The light colored beetle larvae have a distinct, flat enlargement of the body just behind their head. Adults are ¼ to 1 ½-inches-long and the larvae is anywhere between ¼ to 2 inches in length. The legless larvae have dark mouthparts.

Susceptibility

• The pests frequently infest poorly growing, weak and stressed junipers or other trees. Dead or dying trees are equally susceptible to infestation. Certain species of flatheaded borers are also damaging to healthy trees. The pests can enter tree from any point where the females lay eggs, usually in bark crevices, in tree wounds and under the bark.

Damage

• As the larvae hatch, they immediately start to feed through the bark and into sapwood and heartwood. Early signs of infestation include the wilting and discoloration of foliage. There are tiny, flat holes visible in the bark. The area around the holes is often stained with tree sap. Sun-burnt tree areas are common entry sites for the pests. Entire limbs are likely to be killed from infestation and inner damage.

Control

• Try to choose juniper varieties that are best suited to the local growing conditions as this reduces stress on trees. Prevention is the best control strategy as the pests are nearly impossible to control once they have bored into the tree. Do not prune trees between spring and summer as the adult borers are active at this time and are likely to infest fresh wound sites. Prune and remove infested limbs and destroy by burning. Remove and destroy severely affected trees entirely. Control methods primarily include the control of the adult pests with insecticides.