Pine Bark Adelgid

Encyclopedia Article

Description of pine bark adelgids White fuzz on the white pine tree branches are caused by pine bark adelgids

The pine bark adelgid is found throughout the eastern U.S. on white, Scots and Austrian pine trees. These aphid-like insects are covered with a white, cottony material and may be found on the bark of the trunk and larger branches, on the bark of twigs, or at the base of the needles. Trunks of heavily infested trees appear white (as if painted) because of the fuzzy covering on the insects. Pine bark adelgids are sap feeders and suck sap from the phloem, through the bark.

Damage caused by pine bark adelgids

Damage to healthy, well established pine trees is not common, though small, newly transplanted or otherwise stressed trees may suffer from heavy infestations. Populations vary considerably from year to year, apparently in response to weather and predator activity.

What this means is that if the tree is otherwise healthy, spraying is not necessary, and that populations may decline on their own. Large, old trees are not likely to be greatly affected by this pest. I suggest giving the trees “TLC” (tender, loving care) to avoid any further stress and watching to see if the population increases.

Management of pine bark adelgids

Chemical control of the aphids is available if needed. The time to spray is either early spring (before bud break) with dormant oil spray, or in mid-April to May with oil, insecticidal soap, or labeled ornamental tree insecticide. Spray the bark of the trunk and major branches according to label directions as high as you can safely reach. Masses of tiny nymphs on the ground around the base of the tree can also be sprayed if present (in mid-May if it happens at all).  Several applications may be needed.  The cottony covering on the insects will remain on the tree even if the insect is dead.  For that reason it is hard to determine if spraying has been effective.

Do you live in Iowa and have an insect you would like identified?

The Iowa State University Plant & Insect Diagnostic Clinic will identify your insect, provide information on what it eats, life cycle, and if it is a pest the best ways to manage them.  Please see our website for current forms, fees, and instructions on preserving and mailing insects.   

Contact information for each states diagnostic laboratory for U.S. residents.  If you live outside of Iowa please do not submit a sample without contacting the Plant & Insect Diagnostic Clinic.