With pine trees, prolonged stress may be caused not only by drought but also by scorching from wildfires and other factors. This stress often results in attacks by bark beetles (also called engraver beetles or Ips beetles) even during the year following the drought or fire. For example, many pine trees that survived scorching by the Bastrop fire in September 2011 now are dying from engraver beetle attacks.
Symptoms of pine bark beetle infestation are fading (yellow) or red foliage in the top portion of the tree or throughout the crown, masses of resin or pitch tubes resembling popcorn kernels in bark crevices, brown or white sawdust accumulated at the base of the tree and Y- or H - shaped trails made by the attacking beetles between the bark and wood surface. Bark beetle attacks can be prevented by applications of topical or systemic insecticides registered for this purpose.
Usually, however, the first symptom noticed by a landowner is discolored needles. By then, it usually is too late to save the tree. High value pines in yards can be treated with insecticide sprays containing bifenthrin (sold under the trade name Onyx) or permethrin (Astro or Dragnet). They work best when applied prior to the beetle attack.
The Texas A&M Forest Service has developed a systemic insecticide that now is registered by the Environmental Protection Agency to protect pines and hardwood trees against a variety of forest pests, including engraver beetles and wood boring insects. The active ingredient is emamectin benzoate - sold under the trade name of Tree-äge. This insecticide is for restricted use only and must be purchased and applied by a certified pesticide applicator. Insecticides - both systemic and spray applications - are best applied prior to the first beetle attack.
In general, healthy pine trees can defend themselves from engraver beetle attacks with a copious flow of resin without need for insecticides except during and immediately following periods of drought or fire.