Southern Pine Beetle, Pine Engraver Beetle, Ips Bark Beetles

According to the Texas A&M Forest Management, Engraver beetles are small, brown to black, cylindrical insects that attack and kill pine trees by feeding and laying eggs in the inner bark of the tree.

Engraver beetles usually breed harmlessly in fresh logging debris and weakened trees and do not kill a significant number of pine trees to be considered a major pest.

However, when trees are weakened or stressed due to drought or other conditions, engraver beetles may attack and kill a significant number of trees. Almost any aged tree may be attacked, but generally, trees less than 10 years old may be killed by drought alone.

Ips beetle activity occurs every year, and attacks are usually very scattered and involve only a few trees in an infestation. The beetles follow this pattern during drought years, too, but they kill a greater number of scattered trees.

There are three principal species of engraver beetles that attack and kill southern pines. They are the eastern six-spined engraver (Ips calligraphus) which is about 5 mm long, the eastern five-spined engraver (Ips grandicollis) which is about 4 mm long, and the small southern pine engraver (Ips avulsus) which is about 3 mm long.

• The six-spined engraver usually is found in large diameter material such as the tree's trunk and large branches.
• The five-spined engraver usually is found in medium-sized material such as the upper trunk and large branches or in small diameter trees.
• The small southern pine engraver is almost always confined to branches in the top of the tree. It is not uncommon to find all three species in a single tree. If only the small southern pine engraver attacks a tree, the top portion of the crown may die, while the lower limbs remain alive. However, even these trees succumb to the beetles eventually.

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 is of no value for controlling Ips. Cutting a buffer of green, uninfested trees around an area of Ips-killed trees is not recommended either.

In yard situations, watering trees (slow and deep) may be a homeowner's best action to prevent engraver beetle attacks. Prompt removal of visibly infested trees (trees that contain some life stage of the beetle -- egg, larva, pupa, adult) is recommended. 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. Adjacent uninfested pines can be sprayed with a preventive insecticide registered for pine bark beetles (such as Astro; traditional bark beetle insecticides like Lindane and Dursban are probably unavailable). However, 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.

Then there is the environmental concern of spray drift to non-target areas when the insecticide is sprayed into the top of large trees. A neighbor may not appreciate your insecticide drifting onto his property.

According to the Texas A&M Forest Management website, in an infected tree, “small round holes (about the size of a pencil lead) will be visible. Once engraver beetles colonize the tree, it will soon die. The next visible characteristic of attack will be the foliage (needles) of the tree turning from green to yellow to red.

During the heat and drought typical of late summer, the tree's foliage will turn from green to red in about three weeks. But, during winter when temperatures are cooler and there is generally more rain, the needles of a beetle-killed pine tree may remain green for 60 or more days after the tree dies.

Once the needles turn red, the tree is dead and cannot be saved (remember: if the needles are red, the tree is dead). Pine trees seldom survive when engraver beetles have attacked them.”

• Prevention is key. Water, fertilize, and mulch to keep trees at maximum vigor.
• If possible, remove weakened or infested trees to minimize bark beetles and other borer populations.
• If the beetles still threaten, apply an appropriate pesticide.
• Pine engravers have three generations per year and stay active all season.
• Numerous borer species are also a threat, so season-long protection is needed until the trees weather the stressful conditions and regain their vigor.
  
  Ips Bark Pine Beetles (Engraver Beetle) Control & Management | Davey Tree

If you suspect you have a tree infestation, contact an arborist.