Beetle tracks copyright 2012 Pamela Breitberg

Bark beetle is a collective term for a variety of insects that tend to infiltrate trees with dead or dying bark and may inhabit stressed or weak trees insuring their demise. The biggest problem is that some beetles may attack live healthy trees nearby; so any infected dead trees should be removed as quickly as beetles are observed. University of Illinois Urban Extension names two beetles that might be responsible for the tracks in these images. They don’t mention attacks on Oak trees explicitly, but Maple, Mulberry and Serviceberry surround our forest’s Oak. The Oak trees would be the original residents of this natural savannah wetland. Some trees were planted decades ago to define the area as forest. Other trees were “volunteers” as my sister would say, establishing themselves from carried or blown seeds. So if the beetles were originally attracted to either of these neighbors then it’s reasonable to assume that they continued their existence using the stressed or dying Oak in the same space.

Dead Oak copyright 2012 Pamela Breitberg

It’s unclear which of the two beetles that IU’s Urban Extension site notes is responsible for the marks on these trees. Or it could be tracks from some other inhabitant.

• There are numerous beetles that attack bark on trees and thus are categorized as bark beetles. Almost any tree is attacked by bark beetles, particularly that part that is dead or dying. Shothole borer (Scolytus rugulosus) attacks dead and stressed trees. It infests most fruit trees, serviceberry, ornamental fruit trees, mountain ash, elm, and mulberry. Corthylus spp. attack maples, dogwood, sasafras, azaleas, rhododendron and other plants.
  
  

  Oak tree remnants copyright 2012 Pamela Breitberg

Check out the following sites for more information.

• http://urbanext.illinois.edu/focus/barkbeetles.cfm.
• http://urbanext.illinois.edu/hortanswers/detailproblem.cfm?PathogenID=80