Borer Damage in Tree: Cracking, Leaking Bark with Insects Inside

A newly purchased home has a favorite tree with cracking, leaking bark. Close inspection reveals a caterpillar and insects inside the moist cracks.

Diagnosis: Borer Infestation

Borers attack stressed trees. The cracking bark and leaking sap are classic signs of larval tunneling.

Two-Step Treatment

1. Insecticide: Spray trunk with imidacloprid (Merit) to kill larvae under bark.
2. Reduce stress: Fertilize with 10-10-10 at 1 lb per inch of trunk diameter, scattered and watered in deeply.

Healthy trees resist borers. Addressing the underlying stress is as important as killing the current insects.