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MANAGE FORESTS & LAND
  • FOREST HEALTH: EVIDENCE OF BEETLE ATTACKS

     

    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 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 rat      
    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.
    Close-up picture of an Ips pitch tube on the bark of a pine tree
    Close-up picture of an Ips pitch tube on the
    bark of a pine tree.
    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
    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.
    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
    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.




    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 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.
     Extensive activity of Ips bark beetles is shown in the inner bark of a pine tree
    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.







    Circles direct your attention to the nuptial chamber where a male Ips beetle may mate with several females 
    Circles direct your attention to the nuptial chamber
     where a male Ips beetle may mate with several females.
     Each female beetle then constructs a vertical egg gallery from this chamber
    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.



     The circular areas in the bark (indicated by the green ovals) are where the larvae pupated before emerging as adult beetles
    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 are made in the outer bark of pine trees  
    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 beetles chew cone-shaped depressions in pine bark  
    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.











    A close-up view of a sawyer egg niche on pine bark 
    The photo above is a close-up view
    of a sawyer egg niche on pine bark
     Sawyer larvae feed under the bark of dead pine trees
    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.
    Gallery pattern created by the feeding of a sawyer larva 
    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.
     These small dead branches are not an indication of attack by pine engraver beetles

    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.











     


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