Major tree pests are no joke, and each region of the country seems to have their own version of these damaging insects that are defoliating trees and causing massive widespread die-off each year.
As landscape professionals, we are a huge part of the front line defense by choosing the right trees for our clients, keeping trees healthy to minimize vulnerability, and by recognizing particular pests and the telltale signs of damage.
We’re also called upon to make selections for replanting to replace large areas of trees that have succumbed to pest problems.
Look for your region below to learn what’s causing problems in your area and some recommended replacements. It’s also a good idea to read up on every region, as many pests move, continuing to cause irreparable damage to more than one geographic area.
Pest: Emerald Ash Borer
This Asian import was not on the radar in North America before 2002, and since then has done great damage to ash trees in the northeast as well as parts of the eastern Midwest. Emerald ash borers are a dark metallic green beetle, ½” long and 1/8” wide.
Signs of Damage: Leaf canopies begin to wilt and die, followed by a third to one half of branch die-off within one year. Most of the tree canopy will die within two years of first signs of infestation. Look for “D” shaped holes in the bark, 1/8” in diameter, when adult beetles emerge in June.
Affected Trees: All species of North American Ash
Replacement Trees: Any other tree species besides the North American Ash. Depending on your zone, Kentucky coffee tree, zelkova, London plane tree, winged elms, and black gum trees are good choices.
Pest: Gypsy Moth
Only gypsy moths in the caterpillar stage feed — and they’re easy to spot at nearly 2” long. The bodies are very hairy and have five pairs of blue dots followed by six pairs of red dots on their backs. Though rampant in Michigan and Ohio, gypsy moths damage has also been observed in parts of Virginia and West Virginia.
Signs of Damage: Watch out for signs of defoliation in the spring as larva emerges.
Affected Trees: Oak, crabapple, linden, poplar, beech, willow, birch, sweetgum, serviceberry, hawthorn, hickory
Replacement Trees: Ash, sycamore, dogwood, juniper, yew, Indian bean, arborvitae
Pest: Southern Pine Beetle
Though named the “southern” pine beetle, this major pest wreaks havoc in Pennsylvania and New Jersey, through the south and ranging into Texas, Arizona, and New Mexico. Adult beetles bore holes through the bark and lay eggs, with hatching larvae feeding on inner and outer bark. Adult beetles are 1/8” long with cylindrical reddish-brown to black bodies.
Signs of Damage: Look for reddish-brown crowns on trees, white pitch tubes, sawdust as the base of the tree, and numerous holes in the bark.
Affected Trees: most pines including loblolly, shortleaf, Virginia, pond, and pitch
Replacement Trees: Longleaf pine, slash pine, Eastern white pine
Pest: Forest Tent Caterpillar
While identified as a major pest problem in the mid-Atlantic region, forest tent caterpillar leaves a destructive path through many other parts of the country as well. Fully-grown caterpillars are 2” long with blue/black bodies and a row of white, footprint-shaped markings on their backs.
Signs of Damage: Observe signs of defoliation on evergreen trees in the spring and early summer. Deciduous trees are usually not affected because they produce another set of leaves during the same year.
Affected Trees: Quaking aspen, oak, ash, birch, alder, fruit trees, basswood, balsam poplar
Replacement Trees: Red maples, sycamores, and conifers, including pine and spruce
Rocky Mountain Region
Pest: Mountain Pine Beetle
Also known as the Rocky Mountain pine beetle, this native Colorado beetle also creates massive damage in Washington, Oregon, and parts of California. Adult beetles are a tiny 5mm long, creamy tan color when young before turning black as they mature.
Signs of Damage: Needles appear yellowish-red before turning rust colored, then drop in the second year of infestation. Look for holes in the bark, bark stripped away from the trunk (by birds looking for the beetles), boring dust in bark crevices, and pitch tubes.
Affected Trees: All pines except Jeffrey pine
Replacement Trees: Jeffrey pine