Extension Spotlight

Ips pini, or the Engraver Beetles are insects that develop in pines and spruces. Ips are everywhere in the United States. They are attracted to pines and spruces under stress from drought, root injury, disease or defoliation.

These insects are not necessarily lethal to the pines and spruces. Attacks can be limited to the tops of trees and large branches. However, Ips can show a uniform needle discoloration and death like the Dendroctonous bark beetles with the blue stain fungi. This can happen but not always.

The adults of this insect are about an eight to a quarter inch long. They are reddish brown to black. Their rear end is lined with three to six pairs of toothlike spines. The males cut a cavity under the bark which attracts females. The females produce egg galleries in a Y or H pattern. As they create these galleries, they push the sawdust out. So, if you inspect your pines and spruces periodically, look for sawdust at the base of trees or in bark crevices.

How to prevent Ips beetles? You can prevent them by using practices that promote healthy tree growth. Naturally, that becomes more challenging in a drought. It is especially challenging when you have many windbreaks with pines and spruces.

Insecticidal sprays used by drenching the trunk or large limbs is effective. However, there can be multiple overlapping generations of Ips beetles that make it hard to determine exactly when to spray. Think about starting in late February and going until November can be the time the adult Ips beetles enter a pine or spruce. Applying a spring and summer spray can be effective in keeping control of Ips. For further information on Ips Beetles and insecticides effective on them, here is a link to the CSU Fact Sheet on Ips Beetles 5.558: https://extension.colostate.edu/docs/pubs/insect/05558.pdf.

I would recommend that when the temperature starts to consistently get 50 degrees Fahrenheit or above, start inspecting your trees. They will begin to be active on these days. Ips beetles within the bark beetle family have a particular characteristic according to Dave Leatherman, Forest Entomologist. Ips beetles congregate at a susceptible tree to overwhelm its defense mechanisms. He took a sample of bark 12 inches by six inches as the Ips beetles started to emerge and placed it in a plastic container. Over 48 days, 128 Ips beetles emerged. What susceptible tree would ever have a chance? Remember, newly planted trees are susceptible as are those with root injury. Long term or repeated drought can cause root injury.

Water management needs to be practiced throughout the season. Water in the fall before the ground freezes. Water in the winter when there is no snow cover for the month. Water if there is an extended drought. An extended drought is 10-14 days. We have had weeks of drought. Water deeply and not frequently.

Don’t overwater. Overwatering can cause as much damage as underwatering. Roots need oxygen to survive and water. Check the soil with a soil probe before watering and know where the moisture level is currently. Trees take 10 gallons of water per inch diameter of the trunk at knee height.

This is a challenging time and like all living beings, trees need water.