• They are usually less than 6 mm (0.25 inch) long

• Are either black or brown colored

• Male and females bore holes into the side of trees, form a chamber, and then lay eggs.

• Bark beetles mainly attack weakened or dying trees, as there is no sap or resin to deter the insects. 

• They are native to North and Central America, with some species found in Europe and China. 

Authors: Sigrid Netherer, Bradley Matthews, Klaus Katzensteiner, Emma Blackwell, Patrick Henschke, Peter Hietz, Josef Pennerstorfer, Sabine Rosner, Silvia Kukita, Helmut Schume, Axel Schopf

• The scientists wanted to test how the amount of water a tree receives affects the number of bark beetle attacks it experiences. 

• There were 100 trees tested.

• The time range was from May to September in 2013.