Top 10 Tree Pests That Can Destroy Your Yard

#1: Emerald Ash Borer – The Silent Ash Killer

The emerald ash borer (Agrilus planipennis) is one of the most destructive invasive pests to ever hit North America. Metallic green and only half an inch long, this beetle targets ash trees, boring through bark and feeding on the inner phloem. This disrupts nutrient transport, causing thinning crowns, bark splits, and ultimately tree death within just two to four years. Infestations are notoriously hard to detect early because external damage often appears only after irreversible harm has been done. Preventing spread means avoiding the movement of firewood, monitoring for D-shaped exit holes, and considering systemic insecticide treatments for high-value ash trees. Once an infestation is advanced, removal of affected trees is often the only option.

#2: Gypsy Moth – The Leaf-Stripping Invader

Gypsy moth caterpillars (Lymantria dispar dispar) are voracious leaf-eaters that target oaks, birches, aspens, and hundreds of other tree species. Large infestations can completely defoliate trees in a matter of weeks, leaving them vulnerable to disease and drought. The damage isn’t limited to a single year—repeated defoliations can weaken trees to the point of death. You can spot early infestations by looking for small, hairy caterpillars with blue and red spots feeding in spring. Egg masses laid on tree trunks or nearby structures can be scraped off and destroyed. Biological controls, such as introducing natural predators or applying Bacillus thuringiensis (Bt), offer effective, eco-friendly ways to curb populations before they peak.

#3: Asian Longhorned Beetle – The Hardwood Destroyer

The Asian longhorned beetle (Anoplophora glabripennis) attacks a wide variety of hardwood trees, including maples, elms, and willows. Recognizable by its glossy black body with white spots and extremely long antennae, this beetle’s larvae tunnel deep into trunks and branches, cutting off the tree’s ability to transport nutrients. Infested trees often exhibit oozing sap, sawdust-like frass at the base, and perfectly round exit holes. Unfortunately, there’s no effective treatment once a tree is infested—eradication efforts typically involve cutting down and chipping the affected trees to prevent further spread. Vigilance is essential; report suspected sightings to local agricultural authorities immediately.

#4: Tent Caterpillars – The Web-Weaving Defoliators

Tent caterpillars are the architects of unsightly silk nests that cluster in tree branches during spring. Several species, such as the Eastern tent caterpillar (Malacosoma americanum), target fruit and ornamental trees, feeding on new foliage until little remains. While a single year’s infestation might not kill a tree, repeated defoliation stresses it significantly, especially if combined with drought or disease. Removing nests by hand during early morning or evening (when caterpillars are inside) can help control populations. Encouraging birds and beneficial insects that prey on caterpillars also reduces damage naturally, keeping your yard’s ecosystem in balance.

#5: Bark Beetles – The Rapid Tree Invaders

Bark beetles encompass numerous species that bore into coniferous and deciduous trees alike. These tiny beetles tunnel under bark, introducing fungi that block nutrient flow and speed up tree decline. Pine bark beetles, for example, have devastated vast forests in the western United States. Infested trees may display reddish needles, pitch tubes on bark, and boring dust around the base. Healthy, well-watered trees are more resistant, so proper irrigation during drought is a powerful defense. In severe outbreaks, preventive trunk sprays or systemic insecticides applied by professionals may be necessary. Removing and destroying infested wood is critical to preventing spread.

#6: Spotted Lanternfly – The Sap-Sucking Threat

The spotted lanternfly (Lycorma delicatula) is a recent invasive pest in North America, known for its striking black-spotted wings and destructive feeding habits. It targets a wide range of plants, including maples, walnuts, and fruit trees, by piercing bark and sucking sap. This feeding not only weakens trees but also leaves behind sticky honeydew, which fosters sooty mold growth. Infestations can spread rapidly, so early detection is crucial. Scraping egg masses, trapping nymphs, and removing their preferred host plant, the tree-of-heaven (Ailanthus altissima), are effective control measures. In high-risk areas, approved insecticides may be required to protect valuable trees.

#7: Aphids – The Tiny Tree Sappers

Aphids are small, soft-bodied insects that cluster on new growth, sucking plant juices and excreting honeydew that leads to mold. While a light aphid presence may only cause curling leaves, heavy infestations can stunt growth, reduce vigor, and attract other pests like ants. Different species target different trees, including oaks, maples, and pines. Controlling aphids often involves introducing natural predators like ladybugs or lacewings, hosing down infested leaves, and applying insecticidal soaps. Avoiding excessive nitrogen fertilizer can also help, as lush new growth attracts more aphids.

#8: Scale Insects – The Camouflaged Parasites

Scale insects often go unnoticed because they resemble small bumps on bark, branches, or leaves. These pests feed on sap, weakening trees and promoting mold growth. Some species, like armored scale, can be especially stubborn, requiring multiple treatments. Infested trees may show yellowing leaves, dieback, and reduced growth. Effective control starts with encouraging natural predators, such as parasitic wasps, and applying horticultural oils during dormant seasons to smother overwintering eggs. For severe infestations, systemic insecticides may be necessary to eliminate hidden populations.

#9: Leaf Miners – The Hidden Leaf Destroyers

Leaf miners are larvae of various insects that live inside leaves, creating winding, discolored tunnels as they feed. While often more of a cosmetic problem, heavy infestations can weaken young trees or ornamentals, especially when combined with other stressors. Affected leaves may curl, drop prematurely, or appear blotched. Because larvae are protected within the leaf, control can be challenging—removing and destroying infested leaves before larvae mature can help break the cycle. Selecting resistant tree varieties and maintaining healthy soil also reduces susceptibility.

#10: Japanese Beetles – The Voracious Feeders

Japanese beetles (Popillia japonica) are one of the most recognizable lawn and garden pests, with metallic green bodies and coppery wings. Adults feed on leaves, skeletonizing them until only veins remain, while larvae (grubs) damage grass roots. They target a wide array of trees, including lindens, birches, and fruit trees. Hand-picking beetles in early morning when they are sluggish can reduce numbers, as can traps placed away from valuable trees. Preventive treatments targeting grubs in the soil during late summer can also break their life cycle and protect your landscape for the following year.

Protecting Your Yard from Tree Pests

The best defense against destructive pests is a combination of vigilance and proactive care. Healthy trees are less attractive to most pests, so proper watering, mulching, and pruning play a critical role. Regular inspections, especially during peak pest seasons, allow you to catch problems early when they’re easier to manage. Whenever possible, opt for environmentally friendly controls that protect beneficial insects and pollinators. In cases of severe infestation or when dealing with regulated invasive pests, contact your local extension service or a certified arborist for professional advice.