Texas Forest Service logo

Print |   ]

How can I tell if my trees have been attacked by beetles?

Pine engraver beetles (also referred to as Ips beetles or Ips engraver beetles) may attack and kill stressed or injured pine trees.  When these beetles colonize a tree, they leave a characteristic gallery pattern under the bark and other evidence that reveal their presence.  Photographs of typical pine engraver beetle attacks are provided to assist landowners and homeowners in diagnosing the presence of these insects. 

Photographic evidence of beetle attacks
pitch tubes trio Pitch tubes often form on the bark of a pine tree where Ips engraver beetles have attacked the  tree. Notice the reddish color of the pitch tubes and that the attacks tend to be on the bark plates rather than in the bark crevices.
Pitch tubes close up Close-up picture of an Ips pitch tube on the bark of a pine tree.
Boring dust Reddish boring dust that collects in bark crevices and at the base of a pine tree indicates attack by pine engraver beetles. This dust is often an early symptom of attack. In addition, all the needles in the crown of the tree may still be green.
attacked stressed tree red needles The pine tree with red needles has been attacked and killed by pine engraver beetles. Notice that other adjacent pine trees have not been attacked. Engraver beetles tend to select stressed or weakened trees to attack which results in scattered tree mortality.
attacked dead trees This picture shows several pine trees that have been attacked and killed by Ips engraver beetles. Notice that some of the lower branches on the tree in the center still have green needles. This tree is dead and will not recover.
Egg galleries Extensive activity of Ips bark beetles is shown in the inner bark of a pine tree. Notice the vertical egg galleries made by adult beetles (see arrows). Vertical egg galleries made by adult Ips beetles are found between the bark and the wood.
Nuptial chamber Circles direct your attention to the nuptial chamber where a male Ips beetle may mate with several females.
Nuptial chamber close up Each female beetle then constructs a vertical egg gallery from this chamber.
Vertical egg gallery The arrow indicates a vertical egg gallery made by an adult pine engraver beetle (Ips spp.) A female beetle lays her eggs along one side of the gallery. Ips egg galleries are kept free of sawdust. Galleries made by Ips larvae extend from the egg gallery. Notice the width of each larval gallery increases as the larva matures and feeds away from where the egg hatched. Ips larval galleries are packed with sawdust. Vertical egg galleries made by adult Ips beetles are a constant width because adult beetles never get any larger. Larval galleries increase in width because the larvae increase in size as they mature.
Pupated larvae scars in egg galleries This picture of the inner bark of a pine tree that was attacked and killed by the small southern pine engraver (Ips avulsus) shows the typical I-shaped egg galleries made by adult beetles. The circular areas in the bark (indicated by the green ovals) are where the larvae pupated before emerging as adult beetles.
Exit holes Small, circular exit holes are made in the outer bark of pine trees as adult Ips beetles emerge to search for another host tree to attack. The holes are about the diameter of a pencil lead.
Sawyer niche Sawyer beetles chew cone-shaped depressions in pine bark where female beetles lay their eggs. Sawyer egg niches are about 1/4 to 3/8 wide. A common associate of Ips engraver beetles, sawyer beetles lay their eggs on pine bark about the time the tree dies.
Sawyer beetle niche close up

The photo above is a close-up view of a sawyer egg niche on pine bark.

Sawyer larvae Sawyer larvae feed under the bark of dead pine trees. Notice the wide thorax (green circle) just behind the black head. These larvae make a rhythmic chewing sound that is easily heard on a still, warm day. People who hear the chewing sound mistakenly think the noise is made by engraver beetles.
Sawyer larva eating damage This photograph of the inner bark of a pine tree shows the gallery pattern created by the feeding of a sawyer larva. Sawyer adults are round-headed wood borers. Sawyer larvae first feed under the bark and then bore into the wood.
Nondamaged tree Small dead branches, as depicted in this photograph, are not an indication of attack by pine engraver beetles. These small branch flags are common on pine trees in the fall of the year and cause no apparent harm to the tree.