White stuff on my white pine.

Asked October 5, 2019, 5:58 PM EDT

My neighbor noticed a white substance growing on some white pine(?) trees of mine and pointed it out to me today. I've never seen it so I'm contacting you.

Ottawa County Michigan

4 Responses

This is pine bark adelgid.

The pine bark adelgid (Pineus strobe) is found throughout North America and Europe, and it occurs throughout the United States wherever white pines grow. This insect is quite small, dark and covered with white, waxy strands. Infested trees can be recognized by the presence of patches of this white, cottony material on the smooth bark of the trunks and limbs, and at the bases of needles or buds. Heavily infested trees may appear whitewashed. The insect uses its long, needle-like mouthparts to pierce the tree bark and feed on the sap. Feeding is limited to the bark of the tree.

The adelgid overwinters as nymphs and during the first warm days of spring they begin feeding. Eggs are laid early in the spring and begin to hatch in late April in Michigan. These eggs produce both wingless and winged forms. The wingless forms fly off to nearby spruce trees to lay eggs but the offspring from these eggs eventually die. The wingless forms that remain on the white pine produce as many as four more generations during the growing season. Healthy infested trees do not appear to suffer any permanent damage from pine bark adelgids, however, the cottony patches may affect the overall appearance of the tree.

Pine bark adelgids seldom require chemical control measures to protect the health of the tree. If large numbers persist, dormant oil sprays, insecticidal soap and insecticides are effective in killing over-wintering nymphs if applied spring before nymphs mature and lay eggs. Dormant oils, superior (summer) oils, and insecticidal soap will reduce aphid numbers without harming beneficial insects. When using oils, be sure to read and follow all the instructions and safety precautions found on the label to avoid injury to the tree.

Thank you for the info.
I'm concerned for the health of not only these trees but other white pine on my property. How far do these bugs travel? I have a larger, older stand of trees nearby, (20') that are much harder to access in case I need to take them down.
I guess I'm trying to say that I'm willing to take these down to save my other trees and I'm asking you if I need to take this measure.

As I indicated these seldom impact the tree health. Unless the trees show any health issues or are a hazard, I don’t think they need to be removed. Natural predators usually keep populations low. We do some times see outbreaks when homeowners spray for mosquitoes, killing these natural predators.

An option is to contact a ISA Certified Arborists to evaluate your trees. Here is a link to locate an arborist in your area.