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PREVENTION AND CONTROL OF PINE ENGRAVER BEETLES

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Pine engraver beetles (three species of Ips) generally limit their attacks to logging debris and stressed, weakened, or damaged pine trees.  They seldom bother reasonably healthy trees and they tend to attack scattered single trees or those in small groups (2-5 trees).  It is extremely difficult to predict which trees in a forest or yard will be attacked by pine engraver beetles.  Therefore, maintaining healthy trees is a landowner’s best policy for preventing engraver beetle attacks.  In a forest situation, good forest management practices are also good beetle prevention practices.  If direct control is needed for an infestation of engraver beetles in a forest situation, cutting and removing the infested trees is the best course of action to follow.  If only a few trees are involved, doing nothing is often a good choice.  Felling trees and leaving them on site (a control tactic for another pine bark beetle called the southern pine beetle) is of no value for controlling Ips.  In addition, trees from which the beetles have already emerged are not a concern for control.  Cutting a buffer of green, uninfested trees around an area of Ips-killed trees is not recommended either.

In yard situations, root damage caused by construction and drought are the two most common stress factors for pine trees.  Again, maintaining healthy trees is the best way to prevent engraver beetle attacks.  So, watering trees (slow and deep) during periods of drought and avoiding damage to root systems would be good prevention options for a homeowner.  Prompt removal of visibly infested trees (trees that contain some life stage of the beetle -- egg, larva, pupa, adult) is recommended.  Just like in a forest situation, cutting trees from which the beetles have already emerged accomplishes nothing for control.  If a beetle-killed tree is cut, care should be taken to avoid damage to residual, uninfested pine trees.  Damaged trees may be more susceptible to attack by pine beetles.  If Ips-killed trees occur in an area where they could eventually fall on structures, roads, power lines, fences, etc., the trees should be considered a hazard and removed.  Generally, it takes 6-10 months after a pine tree dies for it to become decayed enough for large limbs, the top, or the trunk to break.

Another pine bark beetle of concern in east Texas is the black turpentine beetle (Dendroctonus terebrans).  This beetle readily responds to fresh pine sap (resin, pitch) associated with injured trees.  Like the pine engraver beetles, the black turpentine beetle is not usually a serious problem because its typical attack pattern is to infest scattered trees.  The turpentine beetle is most commonly found in stumps and injured trees associated with construction or logging activity.  Attacks of the black turpentine beetle are usually limited to the bottom six to eight feet of the trunk of the pine tree and a large mass of pitch or resin will usually form where each beetle attacks.  If control is needed, insecticide sprays, if available (see below), can be effective in preventing and controlling this insect.

Uninfested pines adjacent to beetle-killed trees can be sprayed with a preventive insecticide registered for pine bark beetles. Unfortunately these insecticides may be difficult to obtain. Lindane has not been banned, but it is very difficult to find in a formulation for pine bark beetles. Dursban 4E is no longer registered. In yard situations, prompt removal of visibly infested trees is about all that is practical. A chemical called Astro has been used in some areas for pine bark beetles, but I am not aware that it is very effective.  Bottom line -- there presently isn’t much available for pine bark beetle control, period.  Keep in mind that spraying is only recommended for extremely high value trees and in many cases is not practical to apply in urban settings.  Homeowners need to consider the cost of spraying, especially when the tree might not be attacked anyway (remember, Ips beetles tend to attack scattered trees).  Also, if the bark surface from the ground to the crown of the tree is not covered with insecticide, the tree has not been completely protected.  Finally, there is the environmental concern of spray drift to non-target areas when the insecticide is sprayed into the top of tall trees.  A neighbor may not appreciate your insecticide drifting onto his/her property.

On occasion a systemic insecticide may be promoted for pine bark beetles.   This sounds like a great solution to the Ips problem since the insecticide is injected into the tree or taken up by the roots and not sprayed on the tree.  However, this technique has met with certain problemsand is not recommended for pine bark beetles for several reasons.  First, injectors tend to back-fill with pine resin or pitch preventing the insecticide from going into the tree.  Second, even if the insecticide is successfully injected, most of the material is translocated to the top of the tree rather than to the inner bark area where pine bark beetles feed.  Some novel techniques for controlling pine bark beetles have been suggested.  One method involved connecting a 12-volt car battery to a pine tree to electrocute pine bark beetles or their larvae.  This is not effective either.

Sometimes the casual observer may MISTAKENLY think a pine tree is succumbing to pine bark beetles.  During the fall, it is natural for pine trees to contain small branches (called flags) of yellow and red needles scattered through the crown.  Also, discoloration of the second year needles (needles away from the end or tip of the branch) occurs in the fall and during drought stress.  These needles may persist on the branches, and needles that drop from upper branches may lodge on lower branches.  This tends to give the tree’s foliage an off-color or unhealthy appearance.  In addition, an entire branch in the lower crown (usually a lower branch) may die in the fall of the year.  THIS IS NORMAL and does not indicate that pine bark beetles are beginning to attack the tree.  On the other hand, if the upper third or half of the tree’s crown turns red, or ALL the needles have turned red, it is likely the tree has been attacked by pine engraver beetles.  Because of the sometimes confusing color pattern of pine needles in the fall, landowners should be cautious about assuming they have an epidemic of engraver beetles in their trees or timber at this time of year.

The following web sites provide good pictures and other information about the three species of Ips beetles and the black turpentine beetle.

http://fhpr8.srs.fs.fed.us/idotis/insects.html

At the above site, select Conifer Insects, Bark Beetles and Borers, and finally Ips Engraver Beetles and Black Turpentine Beetle.

Also, the Texas A&M Forest Service web site contains information and photographs about pine engraver beetles and how to control them.

Click here for IPS photos