Spruce Ips Bark Beetle

Spruce Ips Bark Beetle - Affecting Spruce trees
                                                
                                                    
                                              First signs of Ips beetle attack, the top of the spruce tree begins dying.


                                             
                                            Spruce Ips Beetle is very small about 3 millimeters or 1/8 of an inch long.


                                             
The inside of a piece of spruce bark cut off of an infested and doomed spruce tree shows several Spruce Ips beetles chewing tunnels to lay eggs along the tunnel. Spruce Ips, is also known as Engraver Beetle, because of the etching in the wood done by the feeding beetles.


                                             
The small holes on the outside of the spruce bark indicate the exit holes of spruce Ips beetle after a brood reaches maturity and is leaving the tree. The holes are frequently hidden by the outer flakes of bark on the spruce. These holes were seen after some outer bark flakes were removed. When these holes are visible the damage is done and the beetles are gone.

         
This picture is taken of a spruce tree, along the trunk, looking down to the ground.  Areas of boring dust (which resembles sawdust) are visible, collecting under outer bark flakes.  The boring dust is made by the Ips beetle chewing its way into or out of a spruce tree.  The beetle pushes the boring dust out of the hole as it chews inside.  The boring dust is not visible looking directly at the trunk of a tree.  Only by getting close to the trunk and looking down can the boring dust be seen.
All photos were taken by City of Cheyenne Urban Forestry Division.

Ips beetles usually attack spruce trees stressed by drought, over-watering, or trees that have been injured.  Visual indications of beetle attacked trees are: faded green color of the needles, or browning needles, dead or dying branches, or the entire tree dying usually starting at the top and working down.  Water your evergreen trees year-round to help keep them healthy.

The Spruce Ips beetles have been causing serious problems along the Colorado Front Range communities for several years.  It was only a matter of time before they appeared in Cheyenne.  The insects come into Cheyenne on primarily firewood and in some cases on nursery stock.  Any spruce wood that has been cut within the previous one year should have the bark removed or covered with two layers of heavy UV resistant clear plastic tarp with the edges securely covered, for at least one year.

Ips beetles have at least two generations per year.  The first generation is probably seen in April to early May.  The second generation is seen in late July to early August.  If late summer and early fall are warm a third generation is possible.

The larva or grub of the beetle kills spruce limbs and spruce trees by feeding on vascular cells under the bark.  Vascular cells form the "circulation" system of the tree transporting water from the root system and food made by the leaves.  Once the circulation has been cut off from a limb or the entire tree, the limb or tree dies.

Quickly cutting down trees that are too heavily infested to survive is important in controlling the insect in Cheyenne.  It is important to spray spruce trees that are stressed or are close to infested trees to reduce the spread of the insect.  City forestry uses Astro a brand name insecticide containing Permethrin to spray on spruce trees in the cemeteries, parks, golf courses and other city maintained land threatened by Ips beetle attack. Water your evergreen trees year-round to help keep them healthy.

For more information, check out this link from Colorado State University.

Links:

Colorado State University Cooperative Extension

University of Wyoming - Cooperative Extension Service, publication B-1035 is particularly helpful for tree care. This online publication contains information on: Aphids, Borers, Cottonwood blotch leaf miners, Cytospora canker, Fireblight, Gall makers, Aspen leaf spots, Oystershell scale, Pear slugs, Powdery mildew, and Spider mites.