Ips Beetles

Ips bark beetles (Ips pini) is also known as the pine engraver beetle for the galleries it leaves behind under pine bark. They are native to our area, and they attack weakened pine and spruce species.

Ips beetles overwinter in the needle debris on the ground, or under the bark of an already-infested tree. Adults then emerge in early Spring. Adult beetles are small (1/8” or smaller), brown, and cylindrical. The males will burrow under the bark of stressed trees. Female beetles are then attracted to the trees where the males have burrowed. After mating, the female beetles then burrow Y- or H-shaped tunnels, where they lay their eggs. The eggs are the size of a pinhead and white. Larvae then hatch and use their jaws to bore tunnels that appear at a right angle to the ones they were laid in. Larvae are also small, creamy white, and have brown heads. The larvae then pupate in those tunnels and then bore to the surface to emerge at adults. Ips can undergo two lifecycles in one Wisconsin Summer.

Ips are typically considered secondary pests. They attack different species of pine and spruce and are attracted to trees that are already weakened from other issues. Trees that are planted in poor, compacted soils or suffer drought or flooding, transplant shock, or construction damage are prime targets for Ips beetles. Although, even the healthiest trees will struggle to fight off an attack if the beetle populations are high enough. With the droughts we’ve seen in recent years, Ips beetle populations have increased, and they are beginning to behave more as a primary pest of pines and spruces in some areas.

The first symptoms you may notice are yellowing or browning of needles, dieback of branches, and small exit holes in the bark. You may also find reddish dust at the base of the tree that result from the beetles’ boring activities. If you look under the bark of infested trees, you will see the tunnels in the wood. You may also see a bluish color surrounding the tunnels, which is caused by a fungus that colonizes the tunnels. This fungus can further damage the vascular tissues they tough.

Ips beetles move quickly and work in large numbers. The boring activities under the bark rapidly destroy the trees’ vascular system, stopping water and nutrients from reaching the needles. Ips infestations can kill trees in as little as one season. Often, by the time all needles have turned yellow/brown, it can be too late to take action. If you suspect your pine or spruce has Ips beetles, contact Tree Health Management to have an ISA Certified Arborist come diagnose your tree. Once we diagnose Ips beetles, there are insecticides available that can stop the progressions of dieback. Keep in mind that if your tree already has sufficient damage to the vascular tissues, it may be not able to translocate the insecticide, and treatments may not work. There are also bark sprays available that can target the beetles while they are outside the tree. Your ISA Certified Arborist will give you the best plan for your tree.

To avoid Ips in the first place, make sure you are taking property cultural controls to keep your trees healthy. Pines and Spruces need a lot of water during the growing season, and into Winter. Established trees should be getting 1 inch of water per week, or about 2 gallons of water per inch in diameter. Anytime we go several days with no rain during the growing season, your spruce or pine should be watered. Using slow soaking methods, such as soaker hoses, is the best practice for watering. Water up until the ground freezes or we get significant snowfall. Maintain a 2-3” layer of mulch over your tree’s root zone as well. Mulch helps the soil to maintain moisture and insulates the roots from temperature extremes. It is good practice to leave the tree’s needles as they fall. Fallen pine needles are the perfect mulch for pine trees. If you are concerned with the health of your pines or spruces, call Tree Health Management today.